Glass compositions, fiberizable glass compositions, and glass fibers made therefrom

ABSTRACT

Embodiments of the present invention provide glass compositions, fiberizable glass compositions, and glass fibers formed from such compositions, as well as glass strands, yarns, fabrics, and composites comprising such glass fibers adapted for use in various applications. In some embodiments of the present invention, the glass compositions additionally include at least one rare earth oxide.

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/047,967, filed on Sep. 9, 2014, which is hereby incorporatedby reference as though fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to glass compositions and, in particular,to glass compositions for forming fibers.

BACKGROUND OF THE INVENTION

Glass fibers have been used to reinforce various polymeric resins formany years. Some commonly used glass compositions for use inreinforcement applications include the “E-glass”, “R-glass”, and“D-glass” families of compositions. “S-glass” is another commonly usedfamily of glass compositions that includes, for example, glass fiberscommercially available from AGY (Aiken, S.C.) under the trade name “S-2Glass.”

In reinforcement and other applications, certain mechanical propertiesof glass fibers or of composites reinforced with glass fibers can beimportant. However, in many instances, the manufacture of glass fibershaving improved mechanical properties (e.g., higher strength, highermodulus, etc.) can result in higher costs due, for example, due toincreased batch material costs, increased manufacturing costs, or otherfactors. For example, the aforementioned “S-2 Glass” has improvedmechanical properties as compared to conventional E-glass but costssignificantly more as well as a result of substantially highertemperature and energy demands for batch-to-glass conversion, meltfining, and fiber drawing. Fiber glass manufacturers continue to seekglass compositions that can be used to form glass fibers havingdesirable mechanical properties in a commercial manufacturingenvironment.

SUMMARY

Various embodiments of the present invention provide glass compositions,fiberizable glass compositions, and glass fibers formed from suchcompositions, as well as fiber glass strands, yarns, fabrics, andcomposites comprising such glass fibers adapted for use in variousapplications.

In one embodiment, a glass composition suitable for fiber formingcomprises 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃; 12 weight percent or less CaO; 7-17 weight percent MgO; 0-1weight percent Na₂O; 0-1 weight percent K₂O; 0-5 weight percent Li₂O;0-2 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percentFe₂O₃; 0-4 weight percent SnO₂; 0-4 weight percent ZnO; at least onerare earth oxide in an amount not less than 0.05 weight percent; and0-11 weight percent total other constituents. In some embodiments, theat least one rare earth oxide comprises at least one of La₂O₃, Y₂O₃,Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxideis present in an amount of at least 1 weight percent in someembodiments. The at least one rare earth oxide, in some embodiments, ispresent in an amount of at least 3 weight percent. In some embodiments,the at least one rare earth oxide is present in an amount up to about 15weight percent. The at least one rare earth oxide, in some embodiments,is present in an amount up to about 8 weight percent. In someembodiments, the at least one rare earth oxide is present in an amountup to about 5 weight percent. In some embodiments, the CaO content isless than about 5 weight percent. The Na₂O+K₂O+Li₂O content is greaterthan 1 weight percent in some embodiments. The Na₂O+K₂O content, in someembodiments, is less than about 0.5 weight percent. In some embodiments,the Al₂O₃ content is between about 14 and about 19 weight percent. MgOis present, in some embodiments, in an amount between about 10 and about16 weight percent. In some embodiments, Li₂O is present in an amountbetween about 0.4 and about 2 weight percent. The glass composition, insome embodiments, comprises at least about 60 weight percent SiO₂. Insome embodiments, ZnO is present in an amount up to about 4 weightpercent. SnO₂ is present, in some embodiments, in an amount up to about4 weight percent. In some embodiments, the at least one rare earth oxidecomprises CeO₂ and CeO₂ is present in an amount up to about 4 weightpercent. In some embodiments, both SnO₂ and CeO₂ are present in acombined amount of up to about 8 weight percent. The glass composition,in some embodiments, further comprises Nb₂O₅ in an amount up to about 5weight percent. In some embodiments, the glass composition issubstantially free of B₂O₃.

In one embodiment, a glass composition suitable for fiber formingcomprises 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃; 5weight percent or less CaO; 10-16 weight percent MgO; 0-1 weight percentNa₂O; 0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-2 weightpercent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-4weight percent SnO₂; 0-4 weight percent ZnO; at least one rare earthoxide in an amount not less than 1 weight percent; and 0-11 weightpercent total other constituents. In some embodiments, the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃,CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent. Insome embodiments, the at least one rare earth oxide is present in anamount up to about 15 weight percent. The at least one rare earth oxide,in some embodiments, is present in an amount up to about 8 weightpercent. In some embodiments, the at least one rare earth oxide ispresent in an amount up to about 5 weight percent. The Na₂O+K₂O+Li₂Ocontent is greater than 1 weight percent in some embodiments. TheNa₂O+K₂O content, in some embodiments, is less than about 0.5 weightpercent. In some embodiments, Li₂O is present in an amount between about0.4 and about 2 weight percent. In some embodiments, ZnO is present inan amount up to about 4 weight percent. SnO₂ is present, in someembodiments, in an amount up to about 4 weight percent. In someembodiments, the at least one rare earth oxide comprises CeO₂ and CeO₂is present in an amount up to about 4 weight percent. In someembodiments, both SnO₂ and CeO₂ are present in a combined amount of upto about 8 weight percent. The glass composition, in some embodiments,further comprises Nb₂O₅ in an amount up to about 5 weight percent. Insome embodiments, the glass composition is substantially free of B₂O₃.

In one embodiment, a glass composition suitable for fiber formingcomprises 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃; 5weight percent or less CaO; 10-16 weight percent MgO; 0-1 weight percentNa₂O; 0-1 weight percent K₂O; 0.4-2 weight percent Li₂O; 0-2 weightpercent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-4weight percent SnO₂; 0-4 weight percent ZnO; at least one rare earthoxide in an amount between about 1 and about 8 weight percent; and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, the at leastone rare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃,Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, insome embodiments, is present in an amount of at least 3 weight percent.In some embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent. The Na₂O+K₂O+Li₂O content isgreater than 1 weight percent in some embodiments. In some embodiments,ZnO is present in an amount up to about 4 weight percent. SnO₂ ispresent, in some embodiments, in an amount up to about 4 weight percent.In some embodiments, the at least one rare earth oxide comprises CeO₂and CeO₂ is present in an amount up to about 4 weight percent. In someembodiments, both SnO₂ and CeO₂ are present in a combined amount of upto about 8 weight percent. The glass composition, in some embodiments,further comprises Nb₂O₅ in an amount up to about 5 weight percent. Insome embodiments, the glass composition is substantially free of B₂O₃.

In one embodiment, a glass composition suitable for fiber formingcomprises 59-62 weight percent SiO₂, 14-19 weight percent Al₂O₃; 4-8weight percent CaO; 6-11 weight percent MgO; 0-1 weight percent Na₂O;0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-3 weight percentTiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-2 weightpercent Cu₂O; 0-3 weight percent SrO; at least one rare earth oxide inan amount not less than 3 weight percent; and 0-11 weight percent totalother constituents. In some embodiments, the at least one rare earthoxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃,and Gd₂O₃. The at least one rare earth oxide is present in an amount ofat least 4 weight percent in some embodiments. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 5weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 15 weight percent. The at least onerare earth oxide, in some embodiments, is present in an amount up toabout 8 weight percent. In some embodiments, the at least one rare earthoxide is present in an amount up to about 5 weight percent. In someembodiments, the CaO content is less than about 8 weight percent. TheNa₂O+K₂O+Li₂O content is greater than 1 weight percent in someembodiments. The Na₂O+K₂O content, in some embodiments, is less thanabout 0.5 weight percent. In some embodiments, the Al₂O₃ content isbetween about 15 and about 18 weight percent. MgO is present, in someembodiments, in an amount between about 8 and about 10 weight percent.In some embodiments, Li₂O is present in an amount between about 0.4 andabout 2 weight percent. The glass composition, in some embodiments,comprises at least about 61 weight percent SiO₂. In some embodiments,SrO is present in an amount up to about 3 weight percent. Cu₂O ispresent, in some embodiments, in an amount up to about 2 weight percent.In some embodiments, the at least one rare earth oxide comprises Y₂O₃and Y₂O₃ is present in an amount up to about 5 weight percent. In someembodiments, both Cu₂O and Y₂O₃ are present in a combined amount of upto about 7 weight percent. The glass composition, in some embodiments,further comprises Nb₂O₅ in an amount up to about 5 weight percent. Insome embodiments, the glass composition is substantially free of B₂O₃.

Some embodiments of the present invention relate to fiber glass strands.A number of fiberizable glass compositions are disclosed herein as partof the present invention, and it should be understand that variousembodiments of the present invention can comprise glass fibers, fiberglass strands, yarns, and other products incorporating glass fibersformed from such compositions.

Some embodiments of the present invention relate to yarns formed from atleast one fiber glass strand formed from a glass composition describedherein. Some embodiments of the present invention relate to fabricsincorporating at least one fiber glass strand formed from a glasscomposition described herein. In some embodiments, a fill yarn used inthe fabric can comprise the at least one fiber glass strand. A warpyarn, in some embodiments, can comprise the at least one fiber glassstrand. In some embodiments, fiber glass strands can be used in bothfill yarns and warp yarns used to form fabrics according to the presentinvention. In some embodiments, fabrics of the present invention cancomprise a plain weave fabric, a twill fabric, a crowfoot fabric, asatin weave fabric, a stitch bonded fabric, or a 3D woven fabric.

Some embodiments of the present invention relate to compositescomprising a polymeric resin and glass fibers formed from one of thevarious glass compositions described herein. The glass fibers can befrom a fiber glass strand according to some embodiments of the presentinvention. In some embodiments, the glass fibers can be incorporatedinto a fabric, such as a woven fabric. For example, the glass fibers canbe in a fill yarn and/or a warp yarn that are woven to form a fabric. Inembodiments where the composite comprises a fabric, the fabric cancomprise a plain weave fabric, a twill fabric, a crowfoot fabric, asatin weave fabric, a stitch bonded fabric, or a 3D woven fabric.

The glass fibers can be incorporated into the composite in other formsas well as discussed in more detail below.

With regard to polymeric resins, composites of the present invention cancomprise one or more of a variety of polymeric resins. In someembodiments, the polymeric resin comprises at least one of polyethylene,polypropylene, polyamide, polyimide, polybutylene terephthalate,polycarbonate, thermoplastic polyurethane, phenolic, polyester, vinylester, polydicyclopentadiene, polyphenylene sulfide, polyether etherketone, cyanate esters, bis-maleimides, and thermoset polyurethaneresins. The polymeric resin can comprise an epoxy resin in someembodiments.

Composites of the present invention can be in a variety of forms and canbe used in a variety of applications. Some examples of potential uses ofcomposites according to some embodiments of the present inventioninclude, without limitation, wind energy (e.g., windmill blades),automotive applications, safety/security applications (e.g., ballisticsarmor), aerospace or aviation applications (e.g., interior floors ofplanes), high pressure vessels or tanks, missile casings, electronics,and others.

These and other embodiments of the present invention are described ingreater detail in the Detailed Description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart showing Young's modulus values relative to the amountof rare earth oxides (RE₂O₃) in various glass compositions.

FIG. 2 is a chart showing pristine fiber tensile strength valuesrelative to the amount of rare earth oxides (RE₂O₃) in various glasscompositions.

FIG. 3 is a chart showing softening and glass transition temperaturesrelative to the amount of rare earth oxides (RE₂O₃) in various glasscompositions.

FIG. 4 is a chart showing linear coefficient of thermal expansionrelative to the amount of scandium oxide (Sc₂O₃) in various glasscompositions.

DETAILED DESCRIPTION

Unless indicated to the contrary, the numerical parameters set forth inthe following specification are approximations that can vary dependingupon the desired properties sought to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all subranges subsumedtherein. For example, a stated range of “1 to 10” should be consideredto include any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more, e.g. 1 to 6.1, and ending with amaximum value of 10 or less, e.g., 5.5 to 10. Additionally, anyreference referred to as being “incorporated herein” is to be understoodas being incorporated in its entirety.

It is further noted that, as used in this specification, the singularforms “a,” “an,” and “the” include plural referents unless expressly andunequivocally limited to one referent.

The present invention relates generally to glass compositions. In oneaspect, the present invention provides glass fibers formed from glasscompositions described herein. In some embodiments, glass fibers of thepresent invention can have improved mechanical properties, such as, forexample, Young's modulus and pristine strength, as compared toconventional E-glass fibers.

Glass compositions of the present invention comprise rare earth oxidesin addition to components typically found in glass compositions such asSiO₂, Al₂O₃, CaO, MgO, and others. Such glass compositions can befiberizable and thus can be used to make fiber glass in variousembodiments. As understood to those of skill in the art, the term “rareearth oxides” refers to oxides incorporating a rare earth metal andincludes oxides of scandium (Sc₂O₃), yttrium (Y₂O₃), and the lanthanideelements (lanthanum (La₂O₃), cerium (Ce₂O₃ and CeO₂), praseodymium(Pr₂O₃), neodymium (Nd₂O₃), promethium (Pm₂O₃), samarium (Sm₂O₃),europium (Eu₂O₃ and EuO), gadolinium (Gd₂O₃), terbium (Tb₂O₃),dysprosium (Dy₂O₃), holmium (Ho₂O₃), erbium (Er₂O₃), thulium (Tm₂O₃),ytterbium (Yb₂O₃), and lutetium (Lu₂O₃)). The rare earth oxides areincluded in the glass compositions of the present invention in amountsthat exceed those wherein the rare earth oxide is present only as atramp material or impurity in a batch material included with a glassbatch to provide another component. The glass compositions, in someembodiments, can comprise a combination of rare earth oxides (e.g., oneor more of various rare earth oxides).

In some embodiments, one or more rare earth oxides can be present in aglass composition in an amount not less than about 0.05 weight percent.The one or more rare earth oxides can be present in an amount not lessthan about 0.5 weight percent in some embodiments. The one or more rareearth oxides can be present in an amount greater than about 3 weightpercent in some embodiments. The one or more rare earth oxides can bepresent, in some embodiments, in an amount up to about 5 weight percentalthough greater amounts can be used in other embodiments. In someembodiments, the one or more rare earth oxides can be present in anamount up to about 8 weight percent. In some embodiments, the one ormore rare earth oxides can be present in an amount up to about 10 weightpercent. The one or more rare earth oxides, in some embodiments, can bepresent in an amount up to about 12 weight percent. The one or more rareearth oxides can be present in an amount up to about 15 weight percentin some embodiments. The one or more rare earth oxides, in someembodiments, can be present in an amount between about 0.05 and about 15weight percent. The one or more rare earth oxides can be present in anamount between about 0.5 and about 15 weight percent in someembodiments. In some embodiments, the one or more rare earth oxides canbe present in an amount between about 2.0 and about 15 weight percent.The one or more rare earth oxides, in some embodiments, can be presentin an amount between about 3.0 and about 15 weight percent. In someembodiments, the one or more rare earth oxides can be present in anamount between about 4.0 and about 15 weight percent. The one or morerare earth oxides can be present in an amount between about 5.0 andabout 15 weight percent in some embodiments. In some embodiments, theone or more rare earth oxides can be present in an amount between about1 and about 8 weight percent. The one or more rare earth oxides, in someembodiments, can be present in an amount between about 3 and about 8weight percent. The one or more rare earth oxides can be present in anamount between about 1 and about 5 weight percent in some embodiments.

The amount of rare earth oxides used in some embodiments can depend onthe particular rare earth oxide used, whether other rare earth oxidesare used in the composition, melt properties of the composition, anddesired properties of the glass fibers to be formed from thecomposition, and others.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise La₂O₃ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of La₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, the inclusion ofLa₂O₃ in glass compositions is believed to have a desirable impact onglass softening temperature and glass transition temperatures as well ason tensile strength, elongation, coefficient of thermal expansion, andother properties of glass fibers formed from the compositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise Y₂O₃ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of Y₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, the inclusion ofY₂O₃ in glass compositions is believed to have a desirable impact onglass softening temperature and glass transition temperature as well ason modulus, tensile strength, elongation, coefficient of thermalexpansion, and other properties of glass fibers formed from thecompositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise Sc₂O₃ in an amount between about 0.5and about 4 weight percent. As set forth above and in the Examplesbelow, other amounts of Sc₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, while the inclusionof Sc₂O₃ in glass compositions is believed to have a desirable impact onsome properties of glass fibers formed from the compositions (e.g.,glass softening temperature, glass transition temperature, coefficientof thermal expansion, etc.), the presence of Sc₂O₃ has also beenobserved to raise the liquidus temperature of the compositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise Nd₂O₃ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of Nd₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, the inclusion ofNd₂O₃ in glass compositions is believed to have a desirable impact onglass softening temperature and glass transition temperature as well ason modulus, tensile strength, elongation, coefficient of thermalexpansion, and other properties of glass fibers formed from thecompositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise Sm₂O₃ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of Sm₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, the inclusion ofSm₂O₃ in glass compositions is believed to have a desirable impact onglass softening temperature and glass transition temperature as well ason modulus, tensile strength, elongation, coefficient of thermalexpansion, and other properties of glass fibers formed from thecompositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise Gd₂O₃ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of Gd₂O₃ can also be included in glass compositionsaccording to some embodiments. In some embodiments, the inclusion ofGd₂O₃ in glass compositions is believed to have a desirable impact onglass softening temperature and glass transition temperature as well ason modulus, tensile strength, elongation, coefficient of thermalexpansion, and other properties of glass fibers formed from thecompositions.

In some embodiments, the rare earth oxide used in glass compositions ofthe present invention can comprise CeO₂ in an amount between about 0.5and about 15 weight percent. As set forth above and in the Examplesbelow, other amounts of CeO₂ can also be included in glass compositionsaccording to some embodiments. For example, in some embodiments, CeO₂can be present in an amount between 0 and about 4 weight percent.Although cerium oxide can be introduced in the stable form of CeO₂, amajority of cerium in the glass, when melted at high temperature,reduces from Ce⁴⁺ (in CeO₂) to Ce³⁺ (becoming Ce₂O₃). In this regard,the inclusion of cerium oxide is believed to improve not only the sonicmodulus and strength of glass fibers formed from the compositions, butalso to increase glass quality through better fining of the glass duringmelting during which cerium oxide releases oxygen bubbles as Ce⁴⁺ ionsin the melt reduce to Ce³⁺ ions.

Various combinations of rare earth oxides can be also used to achievedesirable properties (e.g., tensile strength, modulus, specificstrength, specific modulus, etc.). For example, the selection of aparticular rare earth oxide and its relative amount can impact the fiberdensity which can in turn impact specific strength (tensile strengthdivided by density) and specific modulus (modulus divided by density).Likewise, the selection of a particular rare earth oxide and itsrelative amount can impact melt properties of the glass compositions.For example, as noted above, the presence of Sc₂O₃ in certain amountscan increase the liquidus temperature of a glass composition. Similarly,cerium oxide (Ce₂O₃ and CeO₂) can act as an oxidizing and fining agent,such that in some embodiments, the amount of cerium oxide can be no morethan 4 weight percent. Finally, the selection of a particular rare earthoxide and its relative amount can impact the cost of making the glassfibers due to its impact on melt properties and due its cost as a rawmaterial as the cost of rare earth oxides varies substantially. Ingeneral, for the same amount of rare earth oxide in a glass composition,the melt and mechanical properties of the glass can be controlled byselecting a combination of rare earth oxides with different fieldstrengths as defined by z/r² where z is the charge and r is the radiusof the rare earth cation.

As noted above, glass compositions of the present invention and inparticular, fiberizable glass compositions also include other componentsincluding SiO₂, Al₂O₃, CaO, MgO, and others.

In one embodiment, a glass composition suitable for fiber formingcomprises 51-65 weight percent SiO₂, 12.5-19 weight percent Al₂O₃, 0-16weight percent CaO, 0-12 weight percent MgO, 0-2.5 weight percent Na₂O,0-1 weight percent K₂O, 0-2 weight percent Li₂O, 0-3 weight percentTiO₂, 0-3 weight percent ZrO₂, 0-3 weight percent B₂O₃, 0-3 weightpercent P₂O₅, 0-1 weight percent Fe₂O₃, at least one rare earth oxide inan amount not less than 0.05 weight percent, and 0-11 weight percenttotal other constituents. In some embodiments, the at least one rareearth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, and Nd₂O₃. Theat least one rare earth oxide is present in an amount of at least 1weight percent in some embodiments. The at least one rare earth oxide,in some embodiments, is present in an amount of at least 3 weightpercent.

In one embodiment, a glass composition suitable for fiber formingcomprises 51-65 weight percent SiO₂, 12.5-22 weight percent Al₂O₃, 0-16weight percent CaO, 0-12 weight percent MgO, 0-2.5 weight percent Na₂O,0-1 weight percent K₂O, 0-2 weight percent Li₂O, 0-3 weight percentTiO₂, 0-3 weight percent ZrO₂, 0-3 weight percent B₂O₃, 0-3 weightpercent P₂O₅, 0-1 weight percent Fe₂O₃, at least one rare earth oxide inan amount not less than 0.05 weight percent, and 0-11 weight percenttotal other constituents, wherein the Na₂O+K₂O+Li₂O content is greaterthan 1 weight percent. In some embodiments, the at least one rare earthoxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, and Nd₂O₃. The atleast one rare earth oxide is present in an amount of at least 1 weightpercent in some embodiments. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent.

In one embodiment, a glass composition suitable for fiber formingcomprises 51-63 weight percent SiO₂, 14.5-19 weight percent Al₂O₃,0.5-10 weight percent CaO, 0-12 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0-2 weight percent Li₂O, 0-3 weightpercent TiO₂, 0-3 weight percent ZrO₂, 0-2 weight percent B₂O₃, 0-3weight percent P₂O₅, 0-1 weight percent Fe₂O₃, at least one rare earthoxide in an amount not less than 0.5 weight percent, and 0-11 weightpercent total other constituents. In some embodiments, the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, andNd₂O₃. The at least one rare earth oxide is present in an amount of atleast 1 weight percent in some embodiments. The at least one rare earthoxide, in some embodiments, is present in an amount of at least 3 weightpercent.

In one embodiment, a glass composition suitable for fiber formingcomprises 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃; 12 weight percent or less CaO; 7-17 weight percent MgO; 0-1weight percent Na₂O; 0-1 weight percent K₂O; 0-5 weight percent Li₂O;0-2 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percentFe₂O₃; 0-4 weight percent SnO₂; 0-4 weight percent ZnO; at least onerare earth oxide in an amount not less than 0.05 weight percent; and0-11 weight percent total other constituents. In some embodiments, theat least one rare earth oxide comprises at least one of La₂O₃, Y₂O₃,Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxideis present in an amount of at least 1 weight percent in someembodiments. The at least one rare earth oxide, in some embodiments, ispresent in an amount of at least 3 weight percent. In some embodiments,the at least one rare earth oxide is present in an amount up to about 15weight percent. The at least one rare earth oxide, in some embodiments,is present in an amount up to about 8 weight percent. In someembodiments, the at least one rare earth oxide is present in an amountup to about 5 weight percent.

In one embodiment, a glass composition suitable for fiber formingcomprises 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃; 5weight percent or less CaO; 10-16 weight percent MgO; 0-1 weight percentNa₂O; 0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-2 weightpercent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-4weight percent SnO₂; 0-4 weight percent ZnO; at least one rare earthoxide in an amount not less than 1 weight percent; and 0-11 weightpercent total other constituents. In some embodiments, the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃,CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent. Insome embodiments, the at least one rare earth oxide is present in anamount up to about 15 weight percent. The at least one rare earth oxide,in some embodiments, is present in an amount up to about 8 weightpercent. In some embodiments, the at least one rare earth oxide ispresent in an amount up to about 5 weight percent.

In one embodiment, a glass composition suitable for fiber formingcomprises 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃; 5weight percent or less CaO; 10-16 weight percent MgO; 0-1 weight percentNa₂O; 0-1 weight percent K₂O; 0.4-2 weight percent Li₂O; 0-2 weightpercent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-4weight percent SnO₂; 0-4 weight percent ZnO; at least one rare earthoxide in an amount between about 1 and about 8 weight percent; and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, the at leastone rare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃,Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, insome embodiments, is present in an amount of at least 3 weight percent.In some embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent.

In one embodiment, a glass composition suitable for fiber formingcomprises 59-62 weight percent SiO₂, 14-19 weight percent Al₂O₃; 4-8weight percent CaO; 6-11 weight percent MgO; 0-1 weight percent Na₂O;0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-3 weight percentTiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-2 weightpercent Cu₂O; 0-3 weight percent SrO; at least one rare earth oxide inan amount between about 2 and about 6 weight percent; and 0-11 weightpercent total other constituents, wherein the Na₂O+K₂O content is lessthan about 0.5 weight percent. In some embodiments, the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃,CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent. Insome embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent.

It should be understood that any component of a glass compositiondescribed as being present in amount between about 0 weight percent andanother weight percent is not necessarily required in all embodiments.In other words, such components may be optional in some embodiments,depending of course on the amounts of other components included in thecompositions. Likewise, in some embodiments, glass compositions can besubstantially free of such components, meaning that any amount of thecomponent present in the glass composition would result from thecomponent being present as a trace impurity in a batch material.

Some embodiments of the present invention can be characterized by theamount of SiO₂ present in the glass compositions. SiO₂ can be present inan amount between about 51 and about 65 weight percent and between about51 and about 63 weight percent in some embodiments. SiO₂ can be present,in some embodiments, in an amount between about 54 and about 65 weightpercent and between about 54 and about 63 weight percent. In someembodiments, SiO₂ can be present in an amount between about 59 and about62 weight percent and between about 59 and about 65 weight percent. SiO₂can be present in some embodiments in an amount between about 56 andabout 68 weight percent, and between about 60 and 68 weight percent inothers. The glass compositions, in some embodiments, can comprise atleast 60 weight percent SiO₂.

Some embodiments of the present invention can be characterized by theamount of Al₂O₃ present in the glass compositions. In some embodiments,glass compositions can comprise 12.5 to 22 weight percent Al₂O₃. Al₂O₃can be present, in some embodiments, in an amount between about 12.5 andabout 19 weight percent. Al₂O₃ can be present in an amount between about11 and 20 weight percent in some embodiments. Al₂O₃ can be present, insome embodiments, in an amount between about 14 and 19 weight percent.Al₂O₃ can be present in an amount between about 14.5 and 19 weightpercent in some embodiments. In some embodiments, Al₂O₃ can be presentin an amount between about 15 and 19 weight percent and about 15 and 18weight percent.

Some embodiments of the present invention can be characterized by theamount of CaO present in the glass compositions. CaO can be present inan amount between 0 and about 20 weight percent in some embodiments. CaOcan be present, in some embodiments, in an amount between 0 and about 16weight percent. In some embodiments, CaO can be present in an amountbetween about 0.5 and about 15 weight percent. Glass compositions of thepresent invention, in some embodiments, can comprise between about 0.5and about 14 weight percent. CaO can be present in some embodiments inan amount less than about 12 weight percent. In some embodiments, CaOcan be present in an amount between about 0.5 and about 10 weightpercent. Glass compositions of the present invention, in someembodiments, can comprise less than about 5 weight percent CaO. Glasscompositions of the present invention, in some embodiments, can comprisebetween about 4 and about 8 weight percent CaO.

Some embodiments of the present invention can be characterized by theamount of MgO present in the glass compositions. In some embodiments,glass compositions of the present invention comprise between 0 and about12 weight percent MgO. MgO can be present in an amount up to about 9weight percent in some embodiments. MgO can be present, in someembodiments, in an amount between about 6 and about 9 weight percent orabout 6 and about 11 weight percent. In some embodiments, MgO can bepresent in an amount between about 7 and about 17 weight percent. MgOcan be present, in some embodiments, in an amount between about 10 andabout 16 weight percent.

Some embodiments of the present invention can be characterized by theamount of Na₂O present in the glass compositions. In some embodiments,glass compositions of the present invention can comprise between about 0and about 2.5 weight percent Na₂O. Na₂O can be present, in someembodiments, in an amount between about 0 and about 1.5 weight percent.In some embodiments, Na₂O can be present in an amount up to about 1.5weight percent. Na₂O can be present, in some embodiments, in an amountup to about 1.0 weight percent. In some embodiments, Na₂O can be presentin an amount up to about 0.5 weight percent. In some embodiments, glasscompositions of the present invention comprise less than about 0.1weight percent Na₂O.

Some embodiments of the present invention can be characterized by theamount of K₂O present in the glass compositions. K₂O can be present, insome embodiments, in an amount between about 0 and about 1 weightpercent. In some embodiments, K₂O can be present in an amount up toabout 1 weight percent. In some embodiments, K₂O can be present in anamount up to about 0.5 weight percent. In some embodiments, glasscompositions of the present invention comprise less than about 0.1weight percent K₂O.

Some embodiments of the present invention can be characterized by theamount of Li₂O present in the glass compositions. Glass compositions ofthe present invention, in some embodiments, can comprise between about 0and about 5 weight percent Li₂O. In some embodiments, glass compositionsof the present invention can comprise between about 0 and about 2 weightpercent Li₂O. In some embodiments, Li₂O can be present, in someembodiments, in an amount between about 0.4 and about 2 weight percent.Li₂O can be present, in some embodiments, in an amount between about 0and about 1 weight percent. In some embodiments, Li₂O can be present inan amount up to about 1 weight percent.

Some embodiments of the present invention can be characterized by thetotal amount of Na₂O, K₂O, and Li₂O content. In some embodiments, theNa₂O+K₂O+Li₂O content in glass compositions of the present invention isgreater than 1 weight percent. The Na₂O+K₂O+Li₂O content, in someembodiments, is up to about 2.5 weight percent. In some embodiments, theNa₂O+K₂O+Li₂O content is greater than about 1 weight percent and up toabout 2.5 weight percent.

Some embodiments of the present invention can be characterized by thetotal amount of Na₂O and K₂O content. In some embodiments, the Na₂O+K₂Ocontent in glass compositions of the present invention is less thanabout 0.5 weight percent. The Na₂O+K₂O content, in some embodiments, isup to about 0.3 weight percent. In some embodiments, the Na₂O+K₂Ocontent is up to about 0.1 weight percent.

Some embodiments of the present invention can be characterized by theamount of B₂O₃ present in the glass compositions. B₂O₃ can be present inan amount between about 0 and about 3 weight percent in someembodiments. In some embodiments, B₂O₃ can be present in an amountbetween about 0 and about 2 weight percent. B₂O₃ can be present, in someembodiments, in an amount between about 0 and about 1 weight percent. Insome embodiments, glass compositions of the present invention can besubstantially free of B₂O₃, meaning that any B₂O₃ present in the glasscomposition would result from B₂O₃ being present as a trace impurity ina batch material. In other embodiments, glass compositions of thepresent invention can comprise greater than about 1 weigh percent B₂O₃.In some embodiments, B₂O₃ can be present in an amount up to about 10weight percent.

Some embodiments of the present invention can be characterized by theamount of Fe₂O₃ present in the glass compositions. In some embodiments,Fe₂O₃ can be present in an amount less than 1.0 weight percent. Fe₂O₃can be present, in some embodiments, in an amount between about 0 andabout 0.5 weight percent. In some embodiments, Fe₂O₃ can be present inan amount up to about 0.4 weight percent.

Some embodiments of the present invention can be characterized by theamount of TiO₂ present in the glass compositions. TiO₂ can be present,in some embodiments, in an amount between about 0 and about 3 weightpercent. In some embodiments, TiO₂ can be present in an amount up toabout 3 weight percent. TiO₂ can be present, in some embodiments,between 0 and about 2 weight percent.

Some embodiments of the present invention can be characterized by theamount of Cu₂O present in the glass compositions. Cu₂O can be present,in some embodiments, in an amount between about 0 and about 2 weightpercent. In some embodiments, Cu₂O can be present in an amount up to 2weight percent. Cu₂O can be present, in some embodiments, between 0 andabout 1.5 weight percent. Cu₂O was used in the glass batch, in moltenglass, in a mixture of oxidation states, Cu₁₊ and Cu²⁺ ions, which arebelieved to be stable in the glass. Without wishing to be bound to anytheory, it is believed that monovalent Cu⁺ ions function similar toalkalis and divalent Cu²⁺ ions function similarly to ZnO, therebyimproving the glass chemical durability. The oxidation of the Cu⁺ ion toCu²⁺ ion on glass or glass fiber surface provides the benefit of higherglass and/or glass fiber strength. It is believed that the increasedstrength is provided by the formation of a structural passivation layerthat slows down the penetration of molecular water from the surroundingenvironment into the glass and/or glass fibers.

Some embodiments of the present invention can be characterized by theamount of SrO present in the glass compositions. SrO can be present, insome embodiments, in an amount between about 0 and about 3 weightpercent. In some embodiments, SrO can be present in an amount up to 3weight percent. SrO can be present, in some embodiments, between 0 and2.5 weight percent. SrO has the effect of decreasing glass viscosity ascompared to either MgO or CaO. Therefore, the addition of SrO, asopposed to either MgO or CaO, will result in an improvement to the glasselastic modulus.

In some embodiments, glass compositions of the present invention cancomprise ZnO. ZnO can be used to replace or reduce the amount of CaO insome embodiments of glass compositions. The inclusion of ZnO, in someembodiments, to at least partially replace CaO is believed to improvethe sonic modulus and tensile strength of glass fibers from suchcompositions. Further, ZnO is believed to reduce the CaO activity in theglass melt and thus is believed to lower the risk of crystallization ofwollastonite (CaO.SiO₂) and/or anorthite (CaO.Al₂O₃O.2SiO₃) in the melt.Glass fibers containing higher concentrations of ZnO can also provideimproved resistance to acid corrosion in some embodiments. Inembodiments where ZnO is included, ZnO can be present in an amount up toabout 4 weight percent. In some embodiments where ZnO is included, ZnOcan be present in an amount up to about 4 weight percent and the amountof CaO can be between about 0 and about 5 weight percent.

In some embodiments, glass compositions of the present invention cancomprise tin oxide. Although tin oxide can be introduced in the form ofSnO₂, a majority of tin in the glass, when melted at high temperature,reduces from Sn⁴⁺ (from SnO₂) to Sn²⁺ (becoming SnO). In this regard,the inclusion of tin oxide is believed to improve not only the sonicmodulus and strength of glass fibers formed from the compositions, butalso to increase glass quality through better fining of the glass duringmelting during which tin oxide releases oxygen bubbles as Sn⁴⁺ ions inthe melt reduce to Sn²⁺ ions. In addition, the presence of SnO in theglass, in some embodiments, can permit the at least partial replacementof CaO. Further, the presence of SnO is believed to reduce the CaOactivity in the glass melt and thus is believed to lower the risk ofcrystallization of wollastonite (CaO.SiO₂) and/or anorthite(CaO.Al₂O₃O.2SiO₃) in the melt. In this regard, tin oxide can also beadded in the form of SnO, in some embodiments, without the potentialimpact on fining. In embodiments where tin oxide is included, tin oxidecan be present in an amount up to about 4 weight percent. In someembodiments where tin oxide is included, tin oxide can be present in anamount up to about 4 weight percent and the amount of CaO can be betweenabout 0 and about 5 weight percent.

In some embodiments, glass compositions of the present invention can becharacterized by the amount of SnO₂ and CeO₂. As these oxides can havesimilar effects on the glass melt and fibers formed therefrom, someglass compositions can comprise both SnO₂ and CeO₂. In some embodiments,the SnO₂+CeO₂ content can be up to about 8 weight percent. The SnO₂+CeO₂content, in some embodiments, can be up to about 6 weight percent. TheSnO₂+CeO₂ content can be up to about 4 weight percent in someembodiments. In some embodiments, SnO₂ can be present in an amount up toabout 4 weight percent and CeO₂ can also be present in an amount up toabout 4 weight percent.

Some embodiments of the present invention can be characterized by theamount of ZrO₂ present in the glass compositions. ZrO₂ can be present,in some embodiments, in an amount between about 0 and about 3 weightpercent. In some embodiments, ZrO₂ can be present in an amount up toabout 2 weight percent. In some embodiments, glass compositions of thepresent invention can be substantially free of ZrO₂, meaning that anyZrO₂ present in the glass composition would result from ZrO₂ beingpresent as a trace impurity in a batch material.

Some embodiments of the present invention can be characterized by theamount of P₂O₅ present in the glass compositions. P₂O₅ can be present,in some embodiments, in an amount between about 0 and about 3 weightpercent. In some embodiments, P₂O₅ can be present in an amount up toabout 2.5 weight percent. In some embodiments, glass compositions of thepresent invention can be substantially free of P₂O₅, meaning that anyP₂O₅ present in the glass composition would result from P₂O₅ beingpresent as a trace impurity in a batch material. P₂O₅ functions as aglass network former and, like SiO₂, forms a tetrahedral unit (PO₄) inthe glass. In some embodiments, P₂O₅ can be used to replace SiO₂ tolower the liquidus temperature of glasses containing particularly highconcentrations of rare earth oxides.

Some embodiments of the present invention can be characterized by theamount of niobium oxide (Nb₂O₅) present in the glass compositions. Nb₂O₅functions as a glass network former, but forms octahedral units (NbO₆)as opposed to SiO₂, which as a glass network former forms tetrahedralunits (SiO₄). The substitution of Nb₂O₅ for some SiO₂ content isbelieved to lower melt viscosity. With the presence of both NbO₆ andSiO₄ in alkaline earth-containing aluminosilicate glasses or in alkalicontaining aluminosilicate glasses, both 4-fold (AlO₄) and 6-fold (AlO₆)of aluminum exist, and the presence of a higher concentration of AlO₆results in a higher concentration of Nb₂O₅, which is believed to resultin a lower melt viscosity and a higher sonic modulus and tensilestrength in glass fibers formed from the composition. In embodimentswhere Nb₂O₅ is included, Nb₂O₅ can be present in an amount up to about 5weight percent.

Sulfate (expressed as SO₃) may also be present as a refining agent.Small amounts of impurities may also be present from raw materials orfrom contamination during the melting processes, such as SrO, BaO, Cl₂,P₂O₅, Cr₂O₃, or NiO (not limited to these particular chemical forms).Other refining agents and/or processing aids may also be present such asAs₂O₃, MnO, MnO₂, or Sb₂O₃ (not limited to these particular chemicalforms). These impurities and refining agents, when present, are eachtypically present in amounts less than 0.5% by weight of the total glasscomposition.

As noted above, glass compositions, according to some embodiments of thepresent invention are fiberizable. In some embodiments, glasscompositions of the present invention have forming temperatures (T_(F))desirable for use in commercial fiber glass manufacturing operations. Asused herein, the term “forming temperature” or T_(F), means thetemperature at which the glass composition has a viscosity of 1000 poise(or “log 3 temperature”). Glass compositions of the present invention,in some embodiments, have a forming temperature (T_(F)) ranging fromabout 1250° C. to about 1415° C. In another embodiment, glasscompositions of the present invention have a forming temperature rangingfrom about 1250° C. to about 1350° C. In some embodiments, glasscompositions have a forming temperature ranging from about 1250° C. toabout 1310° C.

Glass compositions of the present invention, in some embodiments, have aliquidus temperature ranging from about 1150° C. to about 1515° C. Insome embodiments, glass compositions of the present invention have aliquidus temperature ranging from about 1130° C. to about 1235° C. Inanother embodiment, glass compositions of the present invention have aliquidus temperature ranging from about 1190° C. to about 1300° C. Insome embodiments, glass compositions of the present invention have aliquidus temperature ranging from about 1190° C. to about 1260° C.

In some embodiments, the difference between the forming temperature andthe liquidus temperature of a glass composition of the present inventionis desirable for commercial fiber glass manufacturing operations. Forexample, for some embodiments of glass compositions, the differencebetween the forming temperature and the liquidus temperature ranges fromabout 35° C. to greater than 60° C. In some embodiments, the differencebetween the forming temperature and the liquidus temperature of a glasscomposition of the present invention is at least 50° C. In otherembodiments, the difference between the forming temperature and theliquidus temperature of the glass composition of the present inventionranges from about 70° C. to about 190° C.

As provided herein, glass fibers can be formed from some embodiments ofthe glass compositions of the present invention. Thus, embodiments ofthe present invention can comprise glass fibers formed from any of theglass compositions described herein. In some embodiments, the glassfibers may be arranged into a fabric. In some embodiments, glass fibersof the present invention can be provided in other forms including, forexample and without limitation, as continuous strands, chopped strands(dry or wet), yarns, rovings, prepregs, etc. In short, variousembodiments of the glass compositions (and any fibers formed therefrom)can be used in a variety of applications.

Some embodiments of the present invention relate to fiber glass strands.Some embodiments of the present invention relate to yarns comprisingfiber glass strands. Some embodiments of yarns of the present inventionare particularly suitable for weaving applications. In addition, someembodiments of the present invention relate to glass fiber fabrics. Someembodiments of fiber glass fabrics of the present invention areparticularly suitable for use in reinforcement applications, especiallyreinforcement applications in which high modulus, high strength, and/orhigh elongation are important. Further, some embodiments of the presentinvention relate to composites that incorporate fiber glass strands,fiber glass yarns, and fiber glass fabrics, such as fiber reinforcedpolymer composites. Some composites of the present invention areparticularly suitable for use in reinforcement applications, especiallyreinforcement applications in which high modulus, high strength, and/orhigh elongation are important, such as wind energy (e.g., windmillblades), automotive applications, safety/security applications (e.g.,ballistics armor or armor panels), aerospace or aviation applications(e.g., interior floors of planes), high pressure vessels or tanks,missile casings, and others. Some embodiments of the present inventionrelate to automotive composites. Some embodiments of the presentinvention relate to aerospace composites. Other embodiments of thepresent application relate to aviation composites. Still otherembodiments of the present invention relate to composites suitable foruse in wind energy applications. Some embodiments of the presentinvention relate to prepregs. Some embodiments of the present inventionrelate to composites for safety/security applications such as armorpanels. Other embodiments of the present invention relate to compositesfor high pressure vessels or storage tanks. Some embodiments of thepresent invention relate to composites for missile casings. Otherembodiments of the present invention relate to composites for use inhigh temperature thermal insulation applications. Some embodiments ofthe present invention relate to printed circuit boards where lowercoefficients of thermal expansion are particularly desirable such assubstrates for chip packaging.

Some embodiments of the present invention relate to fiber glass strands.In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   51-65 weight percent SiO₂;    -   12.5-19 weight percent Al₂O₃;    -   0-16 weight percent CaO;    -   0-12 weight percent MgO;    -   0-2.5 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-2 weight percent Li₂O;    -   0-3 weight percent TiO₂;    -   0-3 weight percent ZrO₂;    -   0-3 weight percent B₂O₃;    -   0-3 weight percent P₂O₅;    -   0-1 weight percent Fe₂O₃;    -   at least one rare earth oxide in an amount not less than 0.05        weight percent; and    -   0-11 weight percent total other constituents.        In some embodiments, the at least one rare earth oxide comprises        at least one of La₂O₃, Y₂O₃, Sc₂O₃, and Nd₂O₃. The at least one        rare earth oxide is present in an amount of at least 1 weight        percent in some embodiments. The at least one rare earth oxide,        in some embodiments, is present in an amount of at least 3        weight percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   51-65 weight percent SiO₂;    -   12.5-22 weight percent Al₂O₃;    -   0-16 weight percent CaO;    -   0-12 weight percent MgO;    -   0-2.5 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-2 weight percent Li₂O;    -   0-3 weight percent TiO₂;    -   0-3 weight percent ZrO₂;    -   0-3 weight percent B₂O₃;    -   0-3 weight percent P₂O₅;    -   0-1 weight percent Fe₂O₃;    -   at least one rare earth oxide in an amount not less than 0.05        weight percent; and    -   0-11 weight percent total other constituents,        wherein the Na₂O+K₂O+Li₂O content is greater than 1 weight        percent. In some embodiments, the at least one rare earth oxide        comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, and Nd₂O₃. The at        least one rare earth oxide is present in an amount of at least 1        weight percent in some embodiments. The at least one rare earth        oxide, in some embodiments, is present in an amount of at least        3 weight percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   51-63 weight percent SiO₂;    -   14.5-19 weight percent Al₂O₃;    -   0.5-10 weight percent CaO;    -   0-12 weight percent MgO;    -   0-1 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-2 weight percent Li₂O;    -   0-3 weight percent TiO₂;    -   0-3 weight percent ZrO₂;    -   0-2 weight percent B₂O₃;    -   0-3 weight percent P₂O₅;    -   0-1 weight percent Fe₂O₃;    -   at least one rare earth oxide in an amount not less than 0.5        weight percent; and    -   0-11 weight percent total other constituents.        In some embodiments, the at least one rare earth oxide comprises        at least one of La₂O₃, Y₂O₃, Sc₂O₃, and Nd₂O₃. The at least one        rare earth oxide is present in an amount of at least 1 weight        percent in some embodiments. The at least one rare earth oxide,        in some embodiments, is present in an amount of at least 3        weight percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   56-68 weight percent SiO₂;    -   11 to less than 20 weight percent Al₂O₃;    -   12 weight percent or less CaO;    -   7-17 weight percent MgO;    -   0-1 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-5 weight percent Li₂O;    -   0-2 weight percent TiO₂;    -   0-3 weight percent B₂O₃;    -   0-1 weight percent Fe₂O₃;    -   0-4 weight percent SnO₂;    -   0-4 weight percent ZnO;    -   at least one rare earth oxide in an amount not less than 0.05        weight percent; and    -   0-11 weight percent total other constituents.        In some embodiments, the at least one rare earth oxide comprises        at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and        Gd₂O₃. The at least one rare earth oxide is present in an amount        of at least 1 weight percent in some embodiments. The at least        one rare earth oxide, in some embodiments, is present in an        amount of at least 3 weight percent. In some embodiments, the at        least one rare earth oxide is present in an amount up to about        15 weight percent. The at least one rare earth oxide, in some        embodiments, is present in an amount up to about 8 weight        percent. In some embodiments, the at least one rare earth oxide        is present in an amount up to about 5 weight percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   60-68 weight percent SiO₂;    -   14-19 weight percent Al₂O₃;    -   5 weight percent or less CaO;    -   10-16 weight percent MgO;    -   0-1 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-2 weight percent Li₂O;    -   0-2 weight percent TiO₂;    -   0-3 weight percent B₂O₃;    -   0-1 weight percent Fe₂O₃;    -   0-4 weight percent SnO₂;    -   0-4 weight percent ZnO;    -   at least one rare earth oxide in an amount not less than 1        weight percent; and    -   0-11 weight percent total other constituents.        In some embodiments, the at least one rare earth oxide comprises        at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and        Gd₂O₃. The at least one rare earth oxide, in some embodiments,        is present in an amount of at least 3 weight percent. In some        embodiments, the at least one rare earth oxide is present in an        amount up to about 15 weight percent. The at least one rare        earth oxide, in some embodiments, is present in an amount up to        about 8 weight percent. In some embodiments, the at least one        rare earth oxide is present in an amount up to about 5 weight        percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   60-68 weight percent SiO₂;    -   14-19 weight percent Al₂O₃;    -   5 weight percent or less CaO;    -   10-16 weight percent MgO;    -   0-1 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0.4-2 weight percent Li₂O;    -   0-2 weight percent TiO₂;    -   0-3 weight percent B₂O₃;    -   0-1 weight percent Fe₂O₃;    -   0-4 weight percent SnO₂;    -   0-4 weight percent ZnO;    -   at least one rare earth oxide in an amount between about 1 and        about 8 weight percent; and    -   0-11 weight percent total other constituents,        wherein the Na₂O+K₂O content is less than about 0.5 weight        percent. In some embodiments, the at least one rare earth oxide        comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂,        Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in some        embodiments, is present in an amount of at least 3 weight        percent. In some embodiments, the at least one rare earth oxide        is present in an amount up to about 5 weight percent.

In some embodiments, a fiber glass strand of the present inventioncomprises a plurality of glass fibers comprising a glass compositionthat comprises the following components:

-   -   59-62 weight percent SiO₂;    -   14-19 weight percent Al₂O₃;    -   4-8 weight percent CaO;    -   6-11 weight percent MgO;    -   0-1 weight percent Na₂O;    -   0-1 weight percent K₂O;    -   0-2 weight percent Li₂O;    -   0-3 weight percent TiO₂;    -   0-3 weight percent B₂O₃;    -   0-1 weight percent Fe₂O₃;    -   0-2 weight percent Cu₂O;    -   0-3 weight percent SrO;    -   at least one rare earth oxide in an amount between about 2 and        about 6 weight percent; and    -   0-11 weight percent total other constituents,

wherein the Na₂O+K₂O content is less than about 0.5 weight percent. Insome embodiments, the at least one rare earth oxide comprises at leastone of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at leastone rare earth oxide, in some embodiments, is present in an amount of atleast 3 weight percent. In some embodiments, the at least one rare earthoxide is present in an amount up to about 5 weight percent.

A number of other glass compositions are disclosed herein as part of thepresent invention, and other embodiments of the present invention relateto fiber glass strands formed from such compositions.

In some embodiments, glass fibers of the present invention can exhibitdesirable mechanical and other properties. Glass fibers of the presentinvention, in some embodiments, can exhibit one or more improvedmechanical properties relative to glass fibers formed from E-glass. Insome embodiments, glass fibers of the present invention can provide oneor more improved properties relative to glass fibers formed from R-glassand/or S-glass. Examples of desirable properties exhibited by someembodiments of glass fibers of the present invention include, withoutlimitation, tensile strength, Young's modulus, coefficient of thermalexpansion, softening point, elongation, and dielectric constant.

Glass fibers of the present invention can have desirable Young's modulus(E) values in some embodiments. In some embodiments, fibers formed fromglass compositions of the present invention can have a Young's modulusgreater than about 87 GPa. In some embodiments, glass fibers of thepresent invention can have a Young's modulus greater than about 90 GPa.Fibers formed from glass compositions of the present invention can havea Young's modulus greater than about 92 GPa in some embodiments. In someembodiments, glass fibers of the present invention can have a Young'smodulus greater than about 93 GPa. Glass fibers of the present inventioncan have a Young's modulus greater than about 95 GPa in someembodiments. Unless otherwise stated herein, Young's modulus valuesdiscussed herein are determined using the procedure set forth in theExamples section below.

Glass fibers of the present invention, in some embodiments, can havedesirable tensile strengths. In some embodiments, glass fibers of thepresent invention can have a tensile strength greater than 4000 MPa.Glass fibers of the present invention, in some embodiments, can have atensile strength greater than 4,500 MPa. In some embodiments, glassfibers of the present invention can have a tensile strength greater thanabout 5000 MPa. Glass fibers of the present invention, in someembodiments, can have a tensile strength greater than about 5500 MPa orgreater than about 5700 MPa. Unless otherwise stated herein, tensilestrength values are determined using the procedure set forth in theExamples section.

Glass fibers of the present invention, in some embodiments, can havedesirable elongation values. In some embodiments, glass fibers of thepresent invention can have an elongation of at least 5.0%. Glass fibersof the present invention can have an elongation of at least 5.5% in someembodiments. Glass fibers of the present invention can have anelongation of at least 6.0% in other embodiments. Unless otherwisestated herein, elongation values are determined using the procedure setforth in the Examples section.

Glass fibers of the present invention, in some embodiments, can havedesirable coefficients of thermal expansion. In some embodiments, glassfibers of the present invention can have a coefficient of thermalexpansion less than about 4.5 ppm/° C. Glass fibers of the presentinvention, in some embodiments, can have a coefficient of thermalexpansion less than about 3.1 ppm/° C. Unless otherwise stated,coefficients of thermal expansion are determined using the procedure setforth in the Examples section.

Glass fibers of the present invention, in some embodiments, can havedesirable softening points. In some embodiments, glass fibers of thepresent invention can have a softening point of at least about 900° C.Glass fibers of the present invention, in some embodiments, can have asoftening point of at least about 950° C. Unless otherwise stated,softening point values are determined using the procedure set forth inthe Examples section.

Glass fibers of the present invention, in some embodiments, can havedielectric constant values (D_(k)) desirable for use in electronicsapplications. In some embodiments, glass fibers of the present inventioncan have a dielectric constant value (D_(k)) of less than about 6.0 at 1MHz frequency. Unless otherwise stated herein, dielectric constant(D_(k)) is determined from 1 MHz to 1 GHz by ASTM Test MethodD150—“Standard Test Methods for A-C Loss Characteristics andPermittivity (Dielectric Constant) of Solid Electrical InsulatingMaterials.”

Fiber glass strands can comprise glass fibers of various diameters,depending on the desired application. In some embodiments, a fiber glassstrand of the present invention comprises at least one glass fiberhaving a diameter between about 5 and about 18 μm. In other embodiments,the at least one glass fiber has a diameter between about 5 and about 10μm.

In some embodiments, fiber glass strands of the present invention can beformed into rovings. Rovings can comprise assembled, multi-end, orsingle-end direct draw rovings. Rovings comprising fiber glass strandsof the present invention can comprise direct draw single-end rovingshaving various diameters and densities, depending on the desiredapplication. In some embodiments, a roving comprising fiber glassstrands of the present invention exhibits a density up to about 112yards/pound.

Some embodiments of the present invention relate to yarns comprising atleast one fiber glass strand as disclosed herein. In some embodiments, ayarn of the present invention comprises at least one fiber glass strandcomprising a glass composition that comprises 56-68 weight percent SiO₂,11 to less than 20 weight percent Al₂O₃, 12 weight percent or less CaO,7-17 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-5 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 0.05 weight percent, and 0-11 weight percent total otherconstituents. A yarn, in some embodiments, comprises at least one fiberglass strand comprising a glass composition that comprises 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, a yarn of the present invention comprises at leastone fiber glass strand comprising a glass composition that comprises60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percentor less CaO, 10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weight percent TiO₂,0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percentSnO₂, 0-4 weight percent ZnO, at least one rare earth oxide in an amountbetween about 1 and about 8 weight percent, and 0-11 weight percenttotal other constituents, wherein the Na₂O+K₂O content is less thanabout 0.5 weight percent. In other embodiments, a yarn of the presentinvention can comprise at least one fiber glass strand comprising one ofthe other glass compositions disclosed herein as part of the presentinvention. In some embodiments, a yarn of the present inventioncomprises at least one fiber glass strand comprising a glass compositionthat comprises 59-62 weight percent SiO₂, 14-19 weight percent Al₂O₃;4-8 weight percent CaO; 6-11 weight percent MgO; 0-1 weight percentNa₂O; 0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-3 weightpercent TiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-2weight percent Cu₂O; 0-3 weight percent SrO; at least one rare earthoxide in an amount between about 2 and about 6 weight percent; and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, the at leastone rare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃,Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, insome embodiments, is present in an amount of at least 3 weight percent.In some embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent.

In some embodiments, a yarn of the present invention comprises at leastone fiber glass strand as disclosed herein, wherein the at least onefiber glass strand is at least partially coated with a sizingcomposition. In some embodiments, the sizing composition is compatiblewith a thermosetting polymeric resin. In other embodiments, the sizingcomposition can comprise a starch-oil sizing composition.

Yarns can have various linear mass densities, depending on the desiredapplication. In some embodiments, a yarn of the present invention has alinear mass density from about 5,000 yards/pound to about 10,000yards/pound.

Yarns can have various twist levels and directions, depending on thedesired application. In some embodiments, a yarn of the presentinvention has a twist in the z direction of about 0.5 to about 2 turnsper inch. In other embodiments, a yarn of the present invention has atwist in the z direction of about 0.7 turns per inch.

Yarns can be made from one or more strands that are twisted togetherand/or plied, depending on the desired application. Yarns can be madefrom one or more strands that are twisted together but not plied; suchyarns are known as “singles.” Yarns of the present invention can be madefrom one or more strands that are twisted together but not plied. Insome embodiments, yarns of the present invention comprise 1-4 strandstwisted together. In other embodiments, yarns of the present inventioncomprise 1 twisted strand.

Some embodiments of the present invention relate to fabrics comprisingat least one fiber glass strand. In some embodiments, a fabric comprisesat least one fiber glass strand comprising a glass composition thatcomprises 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃, 12 weight percent or less CaO, 7-17 weight percent MgO, 0-1weight percent Na₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O,0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percentFe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at least onerare earth oxide in an amount not less than 0.05 weight percent, and0-11 weight percent total other constituents. A fabric, in someembodiments, comprises at least one fiber glass strand comprising aglass composition that comprises 60-68 weight percent SiO₂, 14-19 weightpercent Al₂O₃, 5 weight percent or less CaO, 10-16 weight percent MgO,0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0-2 weight percentLi₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weightpercent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at leastone rare earth oxide in an amount not less than 1 weight percent, and0-11 weight percent total other constituents. In some embodiments, afabric comprises at least one fiber glass strand comprising a glasscomposition that comprises 60-68 weight percent SiO₂, 14-19 weightpercent Al₂O₃, 5 weight percent or less CaO, 10-16 weight percent MgO,0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0.4-2 weight percentLi₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weightpercent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at leastone rare earth oxide in an amount between about 1 and about 8 weightpercent, and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, a fabric comprises at least one fiber glass strandcomprising a glass composition that comprises 59-62 weight percent SiO₂,14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percentMgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent. In otherembodiments, a fabric of the present invention can comprise at least onefiber glass strand comprising one of the other glass compositionsdisclosed herein as part of the present invention. In some embodiments,a fabric of the present invention comprises a yarn as disclosed herein.Fabrics of the present invention, in some embodiments, can comprise atleast one fill yarn comprising at least one fiber glass strand asdisclosed herein. Fabrics of the present invention, in some embodiments,can comprise at least one warp yarn comprising at least one fiber glassstrand as disclosed herein. In some embodiments, a fabric of the presentinvention comprises at least one fill yarn comprising at least one fiberglass strand as disclosed herein and at least one warp yarn comprisingat least one fiber glass strand as disclosed herein.

In some embodiments of the present invention comprising a fabric, theglass fiber fabric is a fabric woven in accordance with industrialfabric style no. 7781. In other embodiments, the fabric comprises aplain weave fabric, a twill fabric, a crowfoot fabric, a satin weavefabric, a stitch bonded fabric (also known as a non-crimp fabric), or a“three-dimensional” woven fabric.

Some embodiments of the present invention relate to composites. In someembodiments, a composite of the present invention comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 56-68 weightpercent SiO₂, 11 to less than 20 weight percent Al₂O₃, 12 weight percentor less CaO, 7-17 weight percent MgO, 0-1 weight percent Na₂O, 0-1weight percent K₂O, 0-5 weight percent Li₂O, 0-2 weight percent TiO₂,0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percentSnO₂, 0-4 weight percent ZnO, at least one rare earth oxide in an amountnot less than 0.05 weight percent, and 0-11 weight percent total otherconstituents. A composite of the present invention, in some embodiments,comprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount not less than 1 weight percent, and 0-11 weightpercent total other constituents. In some embodiments, a composite ofthe present invention comprises a polymeric resin and a plurality ofglass fibers disposed in the polymeric resin, wherein at least one ofthe plurality of glass fibers comprises a glass composition thatcomprises the following components: 60-68 weight percent SiO₂, 14-19weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weight percentMgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0.4-2 weightpercent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO,at least one rare earth oxide in an amount between about 1 and about 8weight percent, and 0-11 weight percent total other constituents,wherein the Na₂O+K₂O content is less than about 0.5 weight percent. Acomposite of the present invention, in some embodiments, comprises apolymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberscomprises a glass composition that comprises the following components:59-62 weight percent SiO₂, 14-19 weight percent Al₂O₃; 4-8 weightpercent CaO; 6-11 weight percent MgO; 0-1 weight percent Na₂O; 0-1weight percent K₂O; 0-2 weight percent Li₂O; 0-3 weight percent TiO₂;0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-2 weight percentCu₂O; 0-3 weight percent SrO; at least one rare earth oxide in an amountbetween about 2 and about 6 weight percent; and 0-11 weight percenttotal other constituents, wherein the Na₂O+K₂O content is less thanabout 0.5 weight percent. In some embodiments, the at least one rareearth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂,Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent. Insome embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent. In other embodiments, a compositeof the present invention can comprise a polymeric resin and a pluralityof glass fibers disposed in the polymeric resin, wherein at least one ofthe plurality of glass fibers was formed from one of the other glasscompositions disclosed herein as part of the present invention. In someembodiments, a composite of the present invention comprises a polymericresin and at least one fiber glass strand as disclosed herein disposedin the polymeric resin. In some embodiments, a composite of the presentinvention comprises a polymeric resin and at least a portion of a rovingcomprising at least one fiber glass strand as disclosed herein disposedin the polymeric resin. In other embodiments, a composite of the presentinvention comprises a polymeric resin and at least one yarn as disclosedherein disposed in the polymeric resin. In still other embodiments, acomposite of the present invention comprises a polymeric resin and atleast one fabric as disclosed herein disposed in the polymeric resin. Insome embodiments, a composite of the present invention comprises atleast one fill yarn comprising at least one fiber glass strand asdisclosed herein and at least one warp yarn comprising at least onefiber glass strand as disclosed herein.

Composites of the present invention can comprise various polymericresins, depending on the desired properties and applications. In someembodiments of the present invention comprising a composite, thepolymeric resin comprises an epoxy resin. In other embodiments of thepresent invention comprising a composite, the polymeric resin cancomprise polyethylene, polypropylene, polyamide, polyimide, polybutyleneterephthalate, polycarbonate, thermoplastic polyurethane, phenolic,polyester, vinyl ester, polydicyclopentadiene, polyphenylene sulfide,polyether ether ketone, cyanate esters, bis-maleimides, and thermosetpolyurethane resins.

Some embodiments of the present invention relate to aerospacecomposites. In some embodiments, an aerospace composite of the presentinvention exhibits properties desirable for use in aerospaceapplications, such as high strength, high elongation, high modulus,and/or low density.

In some embodiments, an aerospace composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃, 12 weight percent or less CaO, 7-17 weight percent MgO, 0-1weight percent Na₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O,0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percentFe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at least onerare earth oxide in an amount not less than 0.05 weight percent, and0-11 weight percent total other constituents. An aerospace composite ofthe present invention, in some embodiments, comprises a polymeric resinand a plurality of glass fibers disposed in the polymeric resin, whereinat least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, an aerospace composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount between about 1 and about 8 weight percent, and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, an aerospacecomposite of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 59-62 weight percent SiO₂,14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percentMgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent. In otherembodiments, an aerospace composite of the present invention cancomprise a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers was formed from one of the other glass compositions disclosedherein as part of the present invention.

In some embodiments, an aerospace composite of the present inventioncomprises a polymeric resin and at least one fiber glass strand asdisclosed herein disposed in the polymeric resin. In some embodiments,an aerospace composite of the present invention comprises a polymericresin and at least a portion of a roving comprising at least one fiberglass strand as disclosed herein disposed in the polymeric resin. Inother embodiments, an aerospace composite of the present inventioncomprises a polymeric resin and at least one yarn as disclosed hereindisposed in the polymeric resin. In still other embodiments, anaerospace composite of the present invention comprises a polymeric resinand at least one fabric as disclosed herein disposed in the polymericresin. In some embodiments, an aerospace composite of the presentinvention comprises at least one fill yarn comprising at least one fiberglass strand as disclosed herein and at least one warp yarn comprisingat least one fiber glass strand as disclosed herein.

Aerospace composites of the present invention can comprise variouspolymeric resins, depending on the desired properties and applications.In some embodiments of the present invention comprising an aerospacecomposite, the polymeric resin comprises an epoxy resin. In otherembodiments of the present invention comprising an aerospace composite,the polymeric resin can comprise polyethylene, polypropylene, polyamide,polyimide, polybutylene terephthalate, polycarbonate, thermoplasticpolyurethane, phenolic, polyester, vinyl ester, polydicyclopentadiene,polyphenylene sulfide, polyether ether ketone, cyanate esters,bis-maleimides, and thermoset polyurethane resins. Examples of parts inwhich aerospace composites of the present invention might be used caninclude, but are not limited to floor panels, overhead bins, galleys,seat back, and other internal compartments that are potentially prone toimpact, as well as external components such as helicopter rotor blades.

Some embodiments of the present invention relate to aviation composites.In some embodiments, an aviation composite of the present inventionexhibits properties desirable for use in aviation applications, such ashigh strength, high elongation, high modulus, lower density, highspecific strength, and/or high specific modulus. The high elongation ofsome aviation composites of the present invention can make suchcomposites especially desirable for use in aviation applications inwhich high impact resistance is important, such as aircraft interiorapplications. In some embodiments, aviation composites of the presentinvention can demonstrate increased impact performance as compared tocomposites formed from E-glass fabrics. Aviation composites of thepresent invention can be suitable for use in aircraft interiors(including, among other things, luggage storage bins, seats, andfloors).

In some embodiments, an aviation composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃, 12 weight percent or less CaO, 7-17 weight percent MgO, 0-1weight percent Na₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O,0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percentFe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at least onerare earth oxide in an amount not less than 0.05 weight percent, and0-11 weight percent total other constituents. An aviation composite ofthe present invention, in some embodiments, comprises a polymeric resinand a plurality of glass fibers disposed in the polymeric resin, whereinat least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, an aviation composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount between about 1 and about 8 weight percent, and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, an aviationcomposite of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 59-62 weight percent SiO₂,14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percentMgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent. In otherembodiments, an aviation composite of the present invention can comprisea polymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberswas formed from one of the other glass compositions disclosed herein aspart of the present invention.

In some embodiments, an aviation composite of the present inventioncomprises a polymeric resin and at least one fiber glass strand asdisclosed herein disposed in the polymeric resin. In some embodiments,an aviation composite of the present invention comprises a polymericresin and at least a portion of a roving comprising at least one fiberglass strand as disclosed herein disposed in the polymeric resin. Inother embodiments, an aviation composite of the present inventioncomprises a polymeric resin and at least one yarn as disclosed hereindisposed in the polymeric resin. In still other embodiments, an aviationcomposite of the present invention comprises a polymeric resin and atleast one fabric as disclosed herein disposed in the polymeric resin. Insome embodiments, an aviation composite of the present inventioncomprises at least one fill yarn comprising at least one fiber glassstrand as disclosed herein and at least one warp yarn comprising atleast one fiber glass strand as disclosed herein.

Aviation composites of the present invention can comprise variouspolymeric resins, depending on the desired properties and applications.In some embodiments of the present invention comprising an aviationcomposite, the polymeric resin comprises a phenolic resin. In otherembodiments of the present invention comprising an aviation composite,the polymeric resin can comprise epoxy, polyethylene, polypropylene,polyamide, polyimide, polybutylene terephthalate, polycarbonate,thermoplastic polyurethane, phenolic, polyester, vinyl ester,polydicyclopentadiene, polyphenylene sulfide, polyether ether ketone,cyanate esters, bis-maleimides, and thermoset polyurethane resins.Examples of parts in which aviation composites of the present inventionmight be used can include, but are not limited to, floor panels,overhead bins, galleys, seat back, and other internal compartments thatare potentially prone to impact, as well as external components such ashelicopter rotor blades.

Some embodiments of the present invention relate to automotivecomposites. In some embodiments, an automotive composite of the presentinvention exhibits properties desirable for use in automotiveapplications, such as high strength, high elongation and low fiberdensity. The combination of high strength and high elongation (orfailure-to-strain) of some composites of the present invention can makesuch composites especially desirable for use in automotive applicationsin which high impact resistance is important, such as automobilestructural components, bodies, and bumpers. In some embodiments,automotive composites of the present invention can demonstrate increasedimpact performance as compared to composites formed from E-glassfabrics, R-glass fabrics, and/or S-glass fabrics.

In some embodiments, an automotive composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 56-68 weight percent SiO₂, 11 to less than 20 weight percentAl₂O₃, 12 weight percent or less CaO, 7-17 weight percent MgO, 0-1weight percent Na₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O,0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percentFe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at least onerare earth oxide in an amount not less than 0.05 weight percent, and0-11 weight percent total other constituents. An automotive composite ofthe present invention, in some embodiments, comprises a polymeric resinand a plurality of glass fibers disposed in the polymeric resin, whereinat least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, an automotive composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount between about 1 and about 8 weight percent, and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, an automotivecomposite of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 59-62 weight percent SiO₂,14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percentMgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent. In otherembodiments, an automotive composite of the present invention cancomprise a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers was formed from one of the other glass compositions disclosedherein as part of the present invention.

In some embodiments, an automotive composite of the present inventioncomprises a polymeric resin and at least one fiber glass strand asdisclosed herein disposed in the polymeric resin. In some embodiments,an automotive composite of the present invention comprises a polymericresin and at least a portion of a roving comprising at least one fiberglass strand as disclosed herein disposed in the polymeric resin. Inother embodiments, an automotive composite of the present inventioncomprises a polymeric resin and at least one yarn as disclosed hereindisposed in the polymeric resin. In still other embodiments, anautomotive composite of the present invention comprises a polymericresin and at least one fabric as disclosed herein disposed in thepolymeric resin. In some embodiments, an automotive composite of thepresent invention comprises at least one fill yarn comprising at leastone fiber glass strand as disclosed herein and at least one warp yarncomprising at least one fiber glass strand as disclosed herein.

Automotive composites of the present invention can comprise variouspolymeric resins, depending on the desired properties and applications.In some embodiments of the present invention comprising an automotivecomposite, the polymeric resin can comprise a thermoplastic resin or athermosetting resin. Examples of common thermoplastic resins used inautomotive composites include, without limitation, polypropylene,polyamide, high temperature polyamide, polyester, and otherthermoplastic resins known to those of skill in the art. Examples ofcommon thermosetting resins used in automotive composites include,without limitation, epoxy, phenolic, polyester, and other thermosettingresins known to those of skill in the art. Examples of parts in whichautomotive composites of the present invention might be used caninclude, but are not limited to, automobile structural components,bodies, and bumpers.

Some embodiments of the present invention relate to composites that canbe used in wind energy applications. In some embodiments, a composite ofthe present invention suitable for use in wind energy applicationsexhibits properties desirable for use in wind energy applications, suchas high modulus, high elongation, low fiber density, and/or highspecific modulus. Composites of the present invention can be suitablefor use in wind turbine blades, particularly long wind turbine bladesthat are lighter weight but still strong compared to other long windturbine blades.

In some embodiments, a composite of the present invention suitable foruse in wind energy applications comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 56-68 weight percent SiO₂, 11to less than 20 weight percent Al₂O₃, 12 weight percent or less CaO,7-17 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-5 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 0.05 weight percent, and 0-11 weight percent total otherconstituents. A composite of the present invention suitable for use inwind energy applications, in some embodiments, comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, a composite of the present invention suitable foruse in wind energy applications comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 60-68 weight percent SiO₂,14-19 weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weightpercent MgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0.4-2weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃,0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percentZnO, at least one rare earth oxide in an amount between about 1 andabout 8 weight percent, and 0-11 weight percent total otherconstituents, wherein the Na₂O+K₂O content is less than about 0.5 weightpercent. In some embodiments, a composite of the present inventionsuitable for use in wind energy applications comprises a polymeric resinand a plurality of glass fibers disposed in the polymeric resin, whereinat least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 59-62 weightpercent SiO₂, 14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11weight percent MgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2weight percent Li₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃;0-1 weight percent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percentSrO; at least one rare earth oxide in an amount between about 2 andabout 6 weight percent; and 0-11 weight percent total otherconstituents, wherein the Na₂O+K₂O content is less than about 0.5 weightpercent. In some embodiments, the at least one rare earth oxidecomprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, andGd₂O₃. The at least one rare earth oxide, in some embodiments, ispresent in an amount of at least 3 weight percent. In some embodiments,the at least one rare earth oxide is present in an amount up to about 5weight percent. In other embodiments, a composite suitable for use inwind energy applications of the present invention can comprise apolymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberswas formed from one of the other glass compositions disclosed herein aspart of the present invention.

In some embodiments, a composite of the present invention suitable foruse in wind energy applications comprises a polymeric resin and at leastone fiber glass strand as disclosed herein disposed in the polymericresin. In some embodiments, a composite of the present inventionsuitable for use in wind energy applications comprises a polymeric resinand at least a portion of a roving comprising at least one fiber glassstrand as disclosed herein disposed in the polymeric resin. In otherembodiments, a composite of the present invention suitable for use inwind energy applications comprises a polymeric resin and at least oneyarn as disclosed herein disposed in the polymeric resin. In still otherembodiments, a composite of the present invention suitable for use inwind energy applications comprises a polymeric resin and at least onefabric as disclosed herein disposed in the polymeric resin. In someembodiments, a composite of the present invention suitable for use inwind energy applications comprises at least one fill yarn comprising atleast one fiber glass strand as disclosed herein and at least one warpyarn comprising at least one fiber glass strand as disclosed herein.

Composites of the present invention suitable for use in wind energyapplications can comprise various polymeric resins, depending on thedesired properties and applications. In some embodiments of the presentinvention comprising a composite suitable for use in wind energyapplications, the polymeric resin comprises an epoxy resin. In otherembodiments of the present invention comprising a composite suitable foruse in wind energy applications, the polymeric resin can comprisepolyester resins, vinyl esters, thermoset polyurethanes, orpolydicyclopentadiene resins.

Some embodiments of the present invention relate to composites for usein high pressure vessels and/or tanks. In some embodiments, a compositefor use in high pressure vessels and/or tanks of the present inventionexhibits properties desirable for use in such applications, such as highstrength, high elongation, low density, and/or high specific strength.

In some embodiments, a composite for use in high pressure vessels and/ortanks of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 56-68 weight percent SiO₂, 11to less than 20 weight percent Al₂O₃, 12 weight percent or less CaO,7-17 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-5 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 0.05 weight percent, and 0-11 weight percent total otherconstituents. A composite for use in high pressure vessels and/or tanksof the present invention, in some embodiments, comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 60-68 weightpercent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percent or less CaO,10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percentK₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weightpercent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4weight percent ZnO, at least one rare earth oxide in an amount not lessthan 1 weight percent, and 0-11 weight percent total other constituents.In some embodiments, a composite for use in high pressure vessels and/ortanks of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 60-68 weight percent SiO₂,14-19 weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weightpercent MgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0.4-2weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃,0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percentZnO, at least one rare earth oxide in an amount between about 1 andabout 8 weight percent, and 0-11 weight percent total otherconstituents, wherein the Na₂O+K₂O content is less than about 0.5 weightpercent. In some embodiments, a composite for use in high pressurevessels and/or tanks of the present invention comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises a glasscomposition that comprises the following components: 59-62 weightpercent SiO₂, 14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11weight percent MgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2weight percent Li₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃;0-1 weight percent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percentSrO; at least one rare earth oxide in an amount between about 2 andabout 6 weight percent; and 0-11 weight percent total otherconstituents, wherein the Na₂O+K₂O content is less than about 0.5 weightpercent. In some embodiments, the at least one rare earth oxidecomprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, andGd₂O₃. The at least one rare earth oxide, in some embodiments, ispresent in an amount of at least 3 weight percent. In some embodiments,the at least one rare earth oxide is present in an amount up to about 5weight percent. In other embodiments, a composite for use in highpressure vessels and/or tanks of the present invention can comprise apolymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberswas formed from one of the other glass compositions disclosed herein aspart of the present invention.

In some embodiments, a composite for use in high pressure vessels and/ortanks of the present invention comprises a polymeric resin and at leastone fiber glass strand as disclosed herein disposed in the polymericresin. In some embodiments, a composite for use in high pressure vesselsand/or tanks of the present invention comprises a polymeric resin and atleast a portion of a roving comprising at least one fiber glass strandas disclosed herein disposed in the polymeric resin. In otherembodiments, a composite for use in high pressure vessels and/or tanksof the present invention comprises a polymeric resin and at least oneyarn as disclosed herein disposed in the polymeric resin. In still otherembodiments, a composite for use in high pressure vessels and/or tanksof the present invention comprises a polymeric resin and at least onefabric as disclosed herein disposed in the polymeric resin. In someembodiments, a composite for use in high pressure vessels and/or tanksof the present invention comprises at least one fill yarn comprising atleast one fiber glass strand as disclosed herein and at least one warpyarn comprising at least one fiber glass strand as disclosed herein.

Composites for use in high pressure vessels and/or tanks of the presentinvention can comprise various polymeric resins, depending on thedesired properties and applications. In some embodiments of the presentinvention comprising a composite for use in high pressure vessels and/ortanks, the polymeric resin can comprise a thermosetting resin. Examplesof common thermosetting resins used in high pressure vessels and/ortanks include, without limitation, epoxy, phenolic, polyester, vinylester and other thermosetting resins known to those of skill in the art.

In some embodiments, composites of the present invention can be usefulin safety and/or security applications. For example, composites of thepresent invention, in some embodiments, are suitable for use in highmechanical stress applications, including, but not limited to, highenergy impact applications. Glass fibers useful in some embodiments ofthe present invention can exhibit properties especially desirable forhigh energy impact applications such as ballistic or blast resistanceapplications. Compared to glass fibers comprising E-glass, glass fibersuseful in some embodiments of the present invention can exhibit lowdielectric constant, low dielectric loss, high glass transitiontemperature and/or low thermal expansion.

In some embodiments, composites of the present invention can be suitablefor use in armor applications. For example, some embodiments ofcomposites can be used in the production of armor panels. In someembodiments, a composite of the present invention can be formed into apanel, wherein the panel are expected to exhibit desirable 0.30 cal FSP(“fragment simulating projectile”) V50 values (e.g., at least about 900feet per second (fps) at a panel areal density of about 2 lb/ft² and apanel thickness of about 5-6 mm) when measured by the U.S. Department ofDefense Test Method Standard for V50 Ballistic Test for Armor,MIL-STD-662F, December 1997 (hereinafter “MIL-STD-662F”), the entiretyof which is incorporated herein by reference. In this context, the term“composite” refers generically to a material comprising a polymericresin and a plurality of glass fibers disposed in the polymeric resin,whereas the term “panel” refers to a composite having sheet-likephysical dimensions or shape. In other embodiments, a composite of thepresent invention can be formed into a panel, wherein the panel isexpected to exhibit desirable 0.50 cal FSP V50 values (e.g., at leastabout 1200 fps at a panel areal density of about 4.8-4.9 lb/ft² and apanel thickness of about 13-13.5 mm) when measured by MIL-STD-662F. AsV50 values can depend on the panel areal density and the panelthickness, composites of the present invention can have different V50values depending on how the panel is constructed. One advantage of someembodiments of the present invention is the provision of compositeshaving higher V50 values than similarly constructed composites assembledusing E-glass fibers.

In some embodiments, a composite of the present invention comprises apolymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberscomprises a glass composition that comprises the following components:56-68 weight percent SiO₂, 11 to less than 20 weight percent Al₂O₃, 12weight percent or less CaO, 7-17 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount not less than 0.05 weight percent, and 0-11 weightpercent total other constituents, wherein the composite is adapted foruse in ballistics or blast resistance applications. A composite of thepresent invention, in some embodiments, comprises a polymeric resin anda plurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 60-68 weight percent SiO₂,14-19 weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weightpercent MgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0-2 weightpercent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO,at least one rare earth oxide in an amount not less than 1 weightpercent, and 0-11 weight percent total other constituents, and whereinthe composite is adapted for use in ballistics or blast resistanceapplications. In some embodiments, a composite of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount between about 1 and about 8 weight percent, and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent, wherein the composite is adapted foruse in ballistics or blast resistance applications. A composite of thepresent invention, in some embodiments, comprises a polymeric resin anda plurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 59-62 weight percent SiO₂,14-19 weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percentMgO; 0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent and wherein thecomposite is adapted for use in ballistics or blast resistanceapplications. In other embodiments, a composite of the present inventionadapted for use in ballistics or blast resistance applications cancomprise a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers was formed from one of the other glass compositions disclosedherein as part of the present invention.

Some embodiments of the present invention relate to panels, such asarmor panels, comprising composites of the present invention. In someembodiments, a composite of the present invention can be formed into apanel, wherein the panel is expected to exhibit desirable 0.30 cal FSPV50 values (e.g., at least about 900 fps at a panel areal density ofabout 2 lb/ft² and a panel thickness of about 5-6 mm) when measured byMIL-STD-662F. In other embodiments, a composite of the present inventioncan be formed into a panel, wherein the panel is expected to exhibitdesirable 0.30 cal FSP V50 values (e.g., at least about 1000 fps at apanel areal density of about 2 lb/ft² and a panel thickness of about 5-6mm) when measured by MIL-STD-662F. In still other embodiments of thepresent invention, a composite can be formed into a panel, wherein thepanel is expected to exhibit desirable 0.30 cal FSP V50 values (e.g., atleast about 1100 fps at a panel areal density of about 2 lb/ft² and apanel thickness of about 5-6 mm) when measured MIL-STD-662F. In someembodiments of the present invention, a composite can be formed into apanel, wherein the panel is expected to exhibit desirable 0.30 cal FSPV50 values (e.g., about 900 fps to about 1140 fps at a panel arealdensity of about 2 lb/ft² and a panel thickness of about 5-6 mm) whenmeasured by MIL-STD-662F.

In some embodiments, a composite of the present invention can be formedinto a panel, wherein the panel is expected to exhibit desirable 0.50cal FSP V50 values (e.g., at least about 1200 fps at a panel arealdensity of about 4.8-4.9 lb/ft² and a panel thickness of about 13-13.5mm) when measured by MIL-STD-662F. In other embodiments of the presentinvention, a composite can be formed into a panel, wherein the panel isexpected to exhibit desirable 0.50 cal FSP V50 values (at least about1300 fps at a panel areal density of about 4.8-4.9 lb/ft² and a panelthickness of about 13-13.5 mm) when measured by MIL-STD-662F. In stillother embodiments of the present invention, a composite can be formedinto a panel, wherein the panel is expected to exhibit desirable 0.50cal FSP V50 values (at least about 1400 fps at a panel areal density ofabout 4.8-4.9 lb/ft² and a panel thickness of about 13-13.5 mm) whenmeasured by MIL-STD-662F. In some embodiments of the present invention,a composite can be formed into a panel, wherein the panel is expected toexhibit desirable 0.50 cal FSP V50 values (e.g., about 1200 fps to about1440 fps at a panel areal density of about 4.8-4.9 lb/ft² and a panelthickness of about 13-13.5 mm) when measured by MIL-STD-662F.

Composites of the present invention adapted for use in ballistics orblast resistance can comprise various polymeric resins. In someembodiments of the present invention, a composite comprises a polymericresin and a plurality of glass fibers disposed in the polymeric resin,wherein at least one of the plurality of glass fibers comprises a glasscomposition as disclosed herein, the composite can be formed into apanel, such as an armor panel for ballistic or blast resistance, and thepolymeric resin comprises an epoxy resin. A composite of the presentinvention, in some embodiments, comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionas disclosed herein, the composite can be formed into a panel, such asan armor panel for ballistic or blast resistance, and the polymericresin comprises a polydicyclopentadiene resin. In some embodiments ofthe present invention, the polymeric resin can comprise polyethylene,polypropylene, polyamides (including Nylon), polybutylene terephthalate,polycarbonate, thermoplastic polyurethane, phenolic, polyester, vinylester, thermoset polyurethane, cyanate esters, or bis-maleimide resins.

Some embodiments of the present invention relate to composites for usein casings for missiles and other explosive delivery devices. In someembodiments, a composite for use in casings for missiles and otherexplosive delivery devices of the present invention exhibits propertiesdesirable for use in such applications, such as high modulus, highstrength, high elongation, low coefficient of thermal expansion, highglass softening temperature, and/or high glass transition temperature.

In some embodiments, a composite for use in casings for missiles andother explosive delivery devices of the present invention comprises apolymeric resin and a plurality of glass fibers disposed in thepolymeric resin, wherein at least one of the plurality of glass fiberscomprises a glass composition that comprises the following components:56-68 weight percent SiO₂, 11 to less than 20 weight percent Al₂O₃, 12weight percent or less CaO, 7-17 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0-5 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount not less than 0.05 weight percent, and 0-11 weightpercent total other constituents. A composite for use in casings formissiles and other explosive delivery devices of the present invention,in some embodiments, comprises a polymeric resin and a plurality ofglass fibers disposed in the polymeric resin, wherein at least one ofthe plurality of glass fibers comprises a glass composition thatcomprises the following components: 60-68 weight percent SiO₂, 14-19weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weight percentMgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0-2 weight percentLi₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃, 0-1 weightpercent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percent ZnO, at leastone rare earth oxide in an amount not less than 1 weight percent, and0-11 weight percent total other constituents. In some embodiments acomposite for use in casings for missiles and other explosive deliverydevices of the present invention comprises a polymeric resin and aplurality of glass fibers disposed in the polymeric resin, wherein atleast one of the plurality of glass fibers comprises a glass compositionthat comprises the following components: 60-68 weight percent SiO₂,14-19 weight percent Al₂O₃, 5 weight percent or less CaO, 10-16 weightpercent MgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0.4-2weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃,0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percentZnO, at least one rare earth oxide in an amount between about 1 andabout 8 weight percent, and 0-11 weight percent total otherconstituents, wherein the Na₂O+K₂O content is less than about 0.5 weightpercent. In some embodiments, a composite for use in casings formissiles and other explosive delivery devices of the present inventioncomprises a polymeric resin and a plurality of glass fibers disposed inthe polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 59-62 weight percent SiO₂, 14-19 weight percent Al₂O₃; 4-8weight percent CaO; 6-11 weight percent MgO; 0-1 weight percent Na₂O;0-1 weight percent K₂O; 0-2 weight percent Li₂O; 0-3 weight percentTiO₂; 0-3 weight percent B₂O₃; 0-1 weight percent Fe₂O₃; 0-2 weightpercent Cu₂O; 0-3 weight percent SrO; at least one rare earth oxide inan amount between about 2 and about 6 weight percent; and 0-11 weightpercent total other constituents, wherein the Na₂O+K₂O content is lessthan about 0.5 weight percent. In some embodiments, the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃,CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rare earth oxide, in someembodiments, is present in an amount of at least 3 weight percent. Insome embodiments, the at least one rare earth oxide is present in anamount up to about 5 weight percent. In other embodiments, a compositefor use in casings for missiles and other explosive delivery devices ofthe present invention can comprise a polymeric resin and a plurality ofglass fibers disposed in the polymeric resin, wherein at least one ofthe plurality of glass fibers was formed from one of the other glasscompositions disclosed herein as part of the present invention.

In some embodiments, a composite for use in casings for missiles andother explosive delivery devices of the present invention comprises apolymeric resin and at least one fiber glass strand as disclosed hereindisposed in the polymeric resin. In some embodiments, a composite foruse in casings for missiles and other explosive delivery devices of thepresent invention comprises a polymeric resin and at least a portion ofa roving comprising at least one fiber glass strand as disclosed hereindisposed in the polymeric resin. In other embodiments, a composite foruse in casings for missiles and other explosive delivery devices of thepresent invention comprises a polymeric resin and at least one yarn asdisclosed herein disposed in the polymeric resin. In still otherembodiments, a composite for use in casings for missiles and otherexplosive delivery devices of the present invention comprises apolymeric resin and at least one fabric as disclosed herein disposed inthe polymeric resin. In some embodiments, a composite for use in casingsfor missiles and other explosive delivery devices of the presentinvention comprises at least one fill yarn comprising at least one fiberglass strand as disclosed herein and at least one warp yarn comprisingat least one fiber glass strand as disclosed herein.

Composites for use in casings for missiles and other explosive deliverydevices of the present invention can comprise various polymeric resins,depending on the desired properties and applications. In someembodiments of the present invention comprising a composite for use incasings for missiles and other explosive delivery devices, the polymericresin can comprise a thermosetting resin. Examples of commonthermosetting resins that can be used in such applications include,without limitation, epoxy, phenolic, polyester, and other thermosettingresins known to those of skill in the art.

While a number of exemplary uses and applications for composites of thepresent invention are described herein, persons of skill in the art canidentify other potential uses for such composites including, forexample, other applications in the oil and gas industry, otherapplications related to transportation and infrastructure, otherapplications in alternative energy, other high temperature thermalinsulation (i.e., thermal shielding) applications (due to higherstrength, higher modulus, higher softening temperature and higher glasstransition temperature), etc.

Some embodiments of the present invention relate to prepregs. Prepregsof the present invention can comprise a polymeric resin and at least onefiber glass strand as disclosed herein. In some embodiments, a prepregof the present invention comprises a polymeric resin and a plurality ofglass fibers in contact with the polymeric resin, wherein at least oneof the plurality of glass fibers comprises a glass composition thatcomprises the following components: 56-68 weight percent SiO₂, 11 toless than 20 weight percent Al₂O₃, 12 weight percent or less CaO, 7-17weight percent MgO, 0-1 weight percent Na₂O, 0-1 weight percent K₂O, 0-5weight percent Li₂O, 0-2 weight percent TiO₂, 0-3 weight percent B₂O₃,0-1 weight percent Fe₂O₃, 0-4 weight percent SnO₂, 0-4 weight percentZnO, at least one rare earth oxide in an amount not less than 0.05weight percent, and 0-11 weight percent total other constituents. Aprepreg of the present invention, in some embodiments, comprises apolymeric resin and a plurality of glass fibers in contact with thepolymeric resin, wherein at least one of the plurality of glass fiberscomprises a glass composition that comprises the following components:60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5 weight percentor less CaO, 10-16 weight percent MgO, 0-1 weight percent Na₂O, 0-1weight percent K₂O, 0-2 weight percent Li₂O, 0-2 weight percent TiO₂,0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4 weight percentSnO₂, 0-4 weight percent ZnO, at least one rare earth oxide in an amountnot less than 1 weight percent, and 0-11 weight percent total otherconstituents. In some embodiments, a prepreg of the present inventioncomprises a polymeric resin and a plurality of glass fibers in contactwith the polymeric resin, wherein at least one of the plurality of glassfibers comprises a glass composition that comprises the followingcomponents: 60-68 weight percent SiO₂, 14-19 weight percent Al₂O₃, 5weight percent or less CaO, 10-16 weight percent MgO, 0-1 weight percentNa₂O, 0-1 weight percent K₂O, 0.4-2 weight percent Li₂O, 0-2 weightpercent TiO₂, 0-3 weight percent B₂O₃, 0-1 weight percent Fe₂O₃, 0-4weight percent SnO₂, 0-4 weight percent ZnO, at least one rare earthoxide in an amount between about 1 and about 8 weight percent, and 0-11weight percent total other constituents, wherein the Na₂O+K₂O content isless than about 0.5 weight percent. In some embodiments, a prepreg ofthe present invention comprises a polymeric resin and a plurality ofglass fibers in contact with the polymeric resin, wherein at least oneof the plurality of glass fibers comprises a glass composition thatcomprises the following components: 59-62 weight percent SiO₂, 14-19weight percent Al₂O₃; 4-8 weight percent CaO; 6-11 weight percent MgO;0-1 weight percent Na₂O; 0-1 weight percent K₂O; 0-2 weight percentLi₂O; 0-3 weight percent TiO₂; 0-3 weight percent B₂O₃; 0-1 weightpercent Fe₂O₃; 0-2 weight percent Cu₂O; 0-3 weight percent SrO; at leastone rare earth oxide in an amount between about 2 and about 6 weightpercent; and 0-11 weight percent total other constituents, wherein theNa₂O+K₂O content is less than about 0.5 weight percent. In someembodiments, the at least one rare earth oxide comprises at least one ofLa₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃. The at least one rareearth oxide, in some embodiments, is present in an amount of at least 3weight percent. In some embodiments, the at least one rare earth oxideis present in an amount up to about 5 weight percent. In otherembodiments, a prepreg of the present invention can comprise a polymericresin and a plurality of glass fibers in contact with the polymericresin, wherein at least one of the plurality of glass fibers was formedfrom one of the other glass compositions disclosed herein as part of thepresent invention.

In some embodiments, a prepreg of the present invention comprises apolymeric resin and at least one fiber glass strand as disclosed hereinin contact with the polymeric resin. In some embodiments, a prepreg ofthe present invention comprises a polymeric resin and at least a portionof a roving comprising at least one fiber glass strand as disclosedherein disposed in the polymeric resin. In other embodiments, a prepregof the present invention comprises a polymeric resin and at least oneyarn as disclosed herein in contact with the polymeric resin. In stillother embodiments, a prepreg of the present invention comprises apolymeric resin and at least one fabric as disclosed herein in contactwith the polymeric resin. In some embodiments, a prepreg of the presentinvention comprises at least one fill yarn comprising at least one fiberglass strand as disclosed herein and at least one warp yarn comprisingat least one fiber glass strand as disclosed herein.

Prepregs of the present invention can comprise various polymeric resins,depending on the desired properties and applications. In someembodiments of the present invention comprising a prepreg, the polymericresin comprises an epoxy resin. In other embodiments of the presentinvention comprising a prepreg, the polymeric resin can comprisepolyethylene, polypropylene, polyamide, polyimide, polybutyleneterephthalate, polycarbonate, thermoplastic polyurethane, phenolic,polyester, vinyl ester, polydicyclopentadiene, polyphenylene sulfide,polyether ether ketone, cyanate esters, bis-maleimides, and thermosetpolyurethane resins.

While many of the applications for the glass fibers described herein arereinforcement applications, some embodiments of glass fibers of thepresent invention can be utilized in electronics applications such asprinted circuit boards (“PCB”). More particularly, some embodiments ofthe present invention relate to glass fiber reinforcements that haveelectrical properties that permit enhancing performance of a PCB. Forexample, some embodiments of glass fibers of the present invention canhave a dielectric constant (D_(k)) desirable for electronicsapplications. The dielectric constant of a material (D_(k)), also knownas “permittivity,” is a measure of the ability of a material to storeelectric energy. A material to be used as a capacitor desirably has arelatively high D_(k), whereas a material to be used as part of a PCBsubstrate desirably has a low D_(k), particularly for high speedcircuits. D_(k) is the ratio of the charge that would be stored (i.e.,the capacitance) of a given material between two metal plates to theamount of charge that would be stored by a void (air or vacuum) betweenthe same two metal plates. As another example, some embodiments of glassfibers of the present invention can have a coefficient for thermalexpansion desirable for electronics applications. Accordingly, someembodiments of the present invention can be used in a variety ofelectrical applications including, without limitation, printed circuitboards, precursors to printed circuit boards (e.g., fabrics, laminates,prepregs, etc.). In such embodiments, the printed circuit board or othercomposite to be used in electrical applications can comprise a polymericresin and a plurality of glass fibers in contact with the polymericresin, wherein at least one of the plurality of glass fibers was formedfrom any of the glass compositions disclosed herein as part of thepresent invention. The polymeric resin can include any of those known tothose of skill in the art for use in printed circuit boards or otherelectrical applications.

Turning now to methods of manufacturing glass fibers of the presentinvention and related products, glass fibers of the present inventioncan be prepared in the conventional manner well known in the art, byblending the raw materials used to supply the specific oxides that formthe composition of the fibers. Glass fibers according to the variousembodiments of the present invention can be formed using any processknown in the art for forming glass fibers, and more desirably, anyprocess known in the art for forming essentially continuous glassfibers. For example, although not limiting herein, the glass fibersaccording to non-limiting embodiments of the present invention can beformed using direct-melt or indirect-melt fiber forming methods. Thesemethods are well known in the art and further discussion thereof is notbelieved to be necessary in view of the present disclosure. See, e.g.,K. L. Loewenstein, The Manufacturing Technology of Continuous GlassFibers, 3rd Ed., Elsevier, N.Y., 1993 at pages 47-48 and 117-234.

Following formation of the glass fibers, a primary sizing compositioncan be applied to the glass fibers using any suitable method known toone of ordinary skill in the art. In some embodiments, the sizingcomposition can be applied immediately after forming the glass fibers.In general, glass fibers used to form fiber glass strands, fabrics,composites, laminates, and prepregs of the present invention will be atleast partially coated with a sizing composition. One skilled in the artmay choose one of many commercially available sizing compositions forthe glass fibers based upon a number of factors including, for example,performance properties of the sizing compositions, desired flexibilityof the resulting fabric, cost, and other factors. In some embodiments,the sizing composition does not comprise a starch-oil sizingcomposition. In some embodiments of the present invention comprising asizing composition that does not comprise a starch-oil sizingcomposition, a sized glass fiber or glass fiber strand need not befurther treated with a slashing composition prior to using the fiber orstrand in weaving applications. In other embodiments comprising a sizingcomposition that does not comprise a starch-oil sizing composition, asized glass fiber or glass fiber strand may optionally be furthertreated with a slashing composition prior to using the fiber or strandin weaving applications. In some embodiments of the present inventioncomprising a primary sizing composition, the sizing composition cancomprise a starch-oil sizing composition. In some embodiments of thepresent invention comprising a starch-oil sizing composition, thestarch-oil sizing composition may later be removed from a fabric formedfrom at least one sized glass fiber or fiber glass strand. In someembodiments, the starch-oil sizing may be removed from a fabric usingany suitable method known to one of ordinary skill in the art, such asbut not limited to heat cleaning. In embodiments of the presentinvention comprising fabrics from which a starch-oil sizing compositionhas been removed, a fabric of the present invention may further betreated with a finish coating.

Non-limiting examples of commercially available sizing compositions thatcan be used in some embodiments of the present invention include sizingcompositions often used on single-end rovings, such as Hybon® 2026,Hybon® 2002, Hybon® 1383, Hybon® 2006, Hybon® 2022, Hybon® 2032, Hybon®2016, and Hybon® 1062, as well as sizing compositions often used onyarns, such as 1383, 611, 900, 610, 695, and 690, each of which refer tosizing compositions for products commercially available from PPGIndustries, Inc.

Fiber glass strands of the present invention can be prepared by anysuitable method known to one of ordinary skill in the art. Glass fiberfabrics of the present invention can generally be made by any suitablemethod known to one of ordinary skill in the art, such as but notlimited to interweaving weft yarns (also referred to as “fill yarns”)into a plurality of warp yarns. Such interweaving can be accomplished bypositioning the warp yarns in a generally parallel, planar array on aloom, and thereafter weaving the weft yarns into the warp yarns bypassing the weft yarns over and under the warp yarns in a predeterminedrepetitive pattern. The pattern used depends upon the desired fabricstyle.

Warp yarns can generally be prepared using techniques known to those ofskill in the art. Warp yarns can be formed by attenuating a plurality ofmolten glass streams from a bushing or spinner. Thereafter, a sizingcomposition can be applied to the individual glass fibers and the fiberscan be gathered together to form a strand. The strands can besubsequently processed into yarns by transferring the strands to abobbin via a twist frame. During this transfer, the strands can be givena twist to aid in holding the bundle of fibers together. These twistedstrands can then be wound about the bobbin, and the bobbins can be usedin the weaving processes.

Positioning of the warp yarns on the loom can generally be done usingtechniques known to those of ordinary skill in the art. Positioning ofthe warp yarns on the loom can be done by way of a loom beam. A loombeam comprises a specified number of warp yarns (also referred to as“ends”) wound in an essentially parallel arrangement (also referred toas “warp sheet”) about a cylindrical core. Loom beam preparation cancomprise combining multiple yarn packages, each package comprising afraction of the number of ends required for the loom beam, into a singlepackage or loom beam. For example and although not limiting herein, a 50inch (127 cm) wide, 7781 style fabric which utilizes a DE75 yarn inputtypically requires 2868 ends. However, conventional equipment forforming a loom beam does not allow for all of these ends to betransferred from bobbins to a single beam in one operation. Therefore,multiple beams comprising a fraction of the number of required ends,typically referred to as “section beams,” can be produced and thereaftercombined to form the loom beam. In a manner similar to a loom beam, asection beam can include a cylindrical core comprising a plurality ofessentially parallel warp yarns wound thereabout. While it will berecognized by one skilled in the art that the section beam can compriseany number of warp yarns required to form the final loom beam, generallythe number of ends contained on a section beam is limited by thecapacity of the warping creel. For a 7781 style fabric, four sectionbeams of 717 ends each of DE75 yarn are typically provided and whencombined offer the required 2868 ends for the warp sheet, as discussedabove.

Composites of the present invention can be prepared by any suitablemethod known to one of ordinary skill in the art, such as but notlimited to vacuum assisted resin infusion molding, extrusioncompounding, compression molding, resin transfer molding, filamentwinding, prepreg/autoclave curing, and pultrusion. Composites of thepresent invention can be prepared using such molding techniques as knownto those of ordinary skill in the art. In particular, embodiments ofcomposites of the present invention that incorporate woven fiber glassfabrics can be prepared using techniques known to those of skill in theart for preparation of such composites.

As an example, some composites of the present invention can be madeusing vacuum assisted compression molding, which technique is well-knownto those of skill in the art and described briefly below. As known tothose of skill in the art, with vacuum assisted compression molding, astack of pre-impregnated glass fabrics is placed within a press platen.In some embodiments of the present invention, the stack ofpre-impregnated glass fabrics can include one or more fabrics of thepresent invention as described herein that have been cut to a desiredsize and shape. Upon completion of the stacking operation for thecorresponding number of layers, the press is closed and the platens areconnected to a vacuum pump so that the upper platen compresses on thestack of fabrics until the desired pressure is achieved. The vacuum aidsin the evacuation of entrapped air within the stack and provides for areduced void content in the molded laminate. Following connection of theplatens to a vacuum pump, the temperature of the platens is thenincreased to accelerate the conversion rate of the resin (e.g., athermosetting resin) to a predetermined temperature setting particularto the resin utilized, and kept at that temperature and pressure settinguntil the laminate reaches full cure. At this point, the heat is turnedoff and the platens are cooled by water circulation until they reachroom temperature. The platens can then be opened, and the moldedlaminate can be removed from the press.

As another example, some composites of the present invention can be madeusing vacuum assisted resin infusion technology, as further describedherein. A stack of glass fiber fabrics of the present invention may becut to a desired size and placed on a silicone release treated glasstable. The stack may then be covered with a peel ply, fitted with a flowenhancing media, and vacuum bagged using nylon bagging film. Next, theso-called “lay up” may be subjected to a vacuum pressure of about 27inches Hg. Separately, the polymeric resin that is to be reinforced withthe fiber glass fabrics can be prepared using techniques known to thoseof skill in the art for that particular resin. For example, for somepolymeric resins, an appropriate resin (e.g., an amine-curable epoxyresin) may be mixed with an appropriate curing agent (e.g., an amine foran amine-curable epoxy resin) in the proportions recommended by theresin manufacturer or otherwise known to a person of ordinary skill inthe art. The combined resin may then be degassed in a vacuum chamber for30 minutes and infused through the fabric preform until substantiallycomplete wet out of the fabric stack is achieved. At this point, thetable may be covered with heated blankets (set to a temperature of about45-50° C.) for 24 hours. The resulting rigid composites may then bede-molded and post cured at about 250° F. for 4 hours in a programmableconvection oven. As is known to persons of ordinary skill in the art,however, various parameters such as degassing time, heating time, andpost curing conditions may vary based on the specific resin system used,and persons of ordinary skill in the art understand how to select suchparameters based on a particular resin system.

Prepregs of the present invention can be prepared by any suitable meansknown to one of ordinary skill in the art, such as but not limited topassing fiber glass strands, rovings, or fabrics through a resin bath;using a solvent-based resin; or using a resin film.

As noted above, composites of the present invention can comprise apolymeric resin, in some embodiments. A variety of polymeric resins canbe used. Polymeric resins that are known to be useful in reinforcementapplications can be particularly useful in some embodiments. In someembodiments, the polymeric resin can comprise a thermoset resin.Thermoset resin systems useful in some embodiments of the presentinvention can include but are not limited to epoxy resin systems,phenolic based resins, polyesters, vinyl esters, thermosetpolyurethanes, polydicyclopentadiene (pDCPD) resins, cyanate esters, andbis-maleimides. In some embodiments, the polymeric resin can comprise anepoxy resin. In other embodiments, the polymeric resin can comprise athermoplastic resin. Thermoplastic polymers useful in some embodimentsof the present invention include but are not limited to polyethylene,polypropylene, polyamides (including Nylon), polybutylene terephthalate,polycarbonate, thermoplastic polyurethanes (TPU), polyphenylenesulfides, and polyether ether ketone (PEEK). Non-limiting examples ofcommercially available polymeric resins useful in some embodiments ofthe present invention include EPIKOTE Resin MGS® RIMR 135 epoxy withEpikure MGS RIMH 1366 curing agent (available from Momentive SpecialtyChemicals Inc. of Columbus, Ohio), Applied Poleramic MMFCS2 epoxy(available from Applied Poleramic, Inc., Benicia, Calif.), and EP255modified epoxy (available from Barrday Composite Solutions, Millbury,Mass.).

The invention will be illustrated through the following series ofspecific embodiments. However, it will be understood by one of skill inthe art that many other embodiments are contemplated by the principlesof the invention.

EXAMPLES

Table 1 provides a plurality of fiberizable glass compositions accordingto various embodiments of the present invention as well as data relatingto various properties of such compositions. Examples 1, 20, 21, 25, 62,and 77 are comparative examples, while the remaining examples representvarious embodiments of the present invention. Table 2 provides aplurality of fiberizable glass compositions according to various otherembodiments of the present invention as well as data relating to variousproperties of such compositions. Table 3 also provides a plurality offiberizable glass compositions according to various other embodiments ofthe present invention as well as data relating to various properties ofsuch compositions.

The glasses in these examples were made by melting mixtures ofcommercial and reagent grade chemicals (reagent grade chemicals wereused only for the rare earth oxides) in powder form in 10% Rh/Ptcrucibles at the temperatures between 1500° C. and 1550° C. (2732° F.2822° F.) for four hours. Each batch was about 1000 grams. After the 4hour melting period, the molten glass was poured onto a steel plate forquenching. Volatile species, such as fluoride and alkali oxides, werenot adjusted in the batches for their emission loss because of their lowconcentrations in the glasses. The compositions in the Examplesrepresent as-batched compositions. Commercial ingredients were used inpreparing the glasses. In the batch calculation, special raw materialretention factors were considered to calculate the oxides in each glass.The retention factors are based on years of glass batch melting andoxides yield in the glass as measured. Hence, the as-batchedcompositions illustrated in the examples are considered to be close tothe measured compositions.

Melt Properties

Melt viscosity as a function of temperature and liquidus temperature wasdetermined by using ASTM Test Method C965 “Standard Practice forMeasuring Viscosity of Glass Above the Softening Point,” and C829“Standard Practices for Measurement of Liquidus Temperature of Glass bythe Gradient Furnace Method,” respectively.

Tables 1-3 include measured liquidus temperature (T_(L)), referencetemperature of forming (T_(F)) defined by melt viscosity of 1000 Poise,and reference temperature of melting (T_(m)) defined by viscosity of 100Poise, for the glass compositions. The difference between the formingtemperature and the liquidus temperature (ΔT) is also shown. Tables 1-3also provide softening temperatures (T_(soft)), glass transitiontemperatures (T_(g)), and coefficients of thermal expansion (CTE) forsome of the compositions. Softening temperature (T_(soft)) values weremeasured in accordance with ASTM Test Method C338-93 “Standard TestMethod for Softening Point of Glass” (2008). Glass transitiontemperature (T_(g)) values were measured in accordance with ASTM TestMethod C336-71 “Annealing Point and Strain Point by Fiber Elongation.”Coefficient of thermal expansion (CTE) values were determined inaccordance with ASTM E228-11 “Standard Test Method for Linear ThermalExpansion of Solid Materials with a Push-Rod Dilatometer.”

Mechanical Properties

For the fiber tensile strength test, fiber samples from the glasscompositions were produced from a 10Rh/90Pt single tip fiber drawingunit. Approximately, 85 grams of cullet of a given composition was fedinto the bushing melting unit and conditioned at a temperature close orequal to the 100 Poise melt viscosity for two hours. The melt wassubsequently lowered to a temperature close or equal to the 1000 Poisemelt viscosity and stabilized for one hour prior to fiber drawing. Fiberdiameter was controlled to produce an approximately 10 μm diameter fiberby controlling the speed of the fiber drawing winder. All fiber sampleswere captured in air without any contact with foreign objects. The fiberdrawing was completed in a room with a controlled humidity of between 40and 45% RH.

Fiber tensile strength was measured using a Kawabata KES-Gl (Kato TechCo. Ltd., Japan) tensile strength analyzer equipped with a Kawabata typeC load cell. Fiber samples were mounted on paper framing strips using aresin adhesive. A tensile force was applied to the fiber until failure,from which the fiber strength was determined based on the fiber diameterand breaking stress. The test was done at room temperature under thecontrolled humidity between 40-45% RH. The average values were computedbased on a sample size of 65-72 fibers for each composition. Tables 1-3report the average tensile strengths for fibers formed from some of thecompositions. Specific strengths were calculated by dividing the tensilestrength values (in N/m²) by the corresponding densities (in g/m³).

Young's modulus was also measured for certain glass compositions inTables 1 and 2 using the following technique. Approximately 50 grams ofglass cullet having a composition corresponding to the appropriateexample in Table 1, Table 2, or Table 3 was re-melted in a 90Pt/10Rhcrucible for two hours at a melting temperature defined by 100 Poise.The crucible was subsequently transferred into a vertical tube,electrically heated furnace. The furnace temperature was preset at afiber pulling temperature close or equal to a 1000 Poise melt viscosity.The glass was equilibrated at the temperature for one hour before fiberdrawing. The top of the fiber drawing furnace had a cover with a centerhole, above which a water-cooled copper coil was mounted to regulate thefiber cooling. A silica rod was then manually dipped into the meltthrough the cooling coil, and a fiber about 1-1.5 m long was drawn outand collected. The diameter of the fiber ranged from 100μ at one end to1000 μm at the other end.

Elastic moduli were determined using an ultrasonic acoustic pulsetechnique (Panatherm 5010 unit from Panametrics, Inc. of Waltham, Mass.)for the fibers drawn from the glass melts. Extensional wave reflectiontime was obtained using twenty micro-second duration, 200 kHz pulses.The sample length was measured and the respective extensional wavevelocity (V_(E)) was calculated. Fiber density (ρ) was measured using aMicromeritics AccuPyc 1330 pycnometer. About 20 measurements were madefor each composition and the average Young's modulus (E) was calculatedfrom the following formula:E=V _(E) ²×ρThe modulus tester uses a wave guide with a diameter of 1 mm, which setsthe fiber diameter at the contact side with the wave guide to be aboutthe same as the wave guide diameter. In other words, the end of thefiber having a diameter of 1000 μm was connected at the contact side ofthe wave guide. Fibers with various diameters were tested for Young'smodulus and the results show that a fiber diameter from 100 to 1000 μmdoes not affect fiber modulus. Specific modulus values were calculatedby dividing the Young's modulus values by the corresponding densities.

The values of “Fiber Failure strain (%)” (i.e., fiber elongation) inTables 1-3 were determined based on Hooke's law by dividing the tensilestrength values by the corresponding Young's modulus values (in the sameunits (e.g., all in MPa)), and multiplying by 100.

TABLE 1 1 2 3 4 5 6 SiO₂ 61.49 61.46 61.37 61.46 61.37 61.46 Al₂O₃ 15.2815.36 15.57 15.36 15.57 15.36 Fe₂O₃ 0.29 0.29 0.29 0.29 0.29 0.29 CaO15.43 13.18 12.51 13.18 12.51 13.18 MgO 6.12 6.26 6.21 6.26 6.21 6.26Na₂O 0.05 0.05 0.05 0.05 0.05 0.05 K₂O 0.09 0.09 0.09 0.09 0.09 0.09Sc₂O₃ 0.00 2.08 2.68 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.00 2.08 2.68 0.00La₂O₃ 0.00 0.00 0.00 0.00 0.00 2.08 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00TiO₂ 0.50 0.50 0.51 0.50 0.51 0.50 Li₂O 0.74 0.72 0.72 0.72 0.72 0.72SO₃ 0.01 0.01 0.01 0.01 0.01 0.01 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00 100.00100.00 100.00 T_(L) (° C.) 1198 1197 1241 1197 1201 1199 T_(F) (° C.)1285 1288 1296 1306 1312 1300 ΔT (° C.) 87 91 55 109 111 101 T_(m) (°C.) 1489 1485 1495 1509 1513 1507 Fiber Density 2.62 2.62 2.62 2.62 2.632.63 (g/cm³) Fiber Modulus (GPa) 89.2 91.0 91.6 90.6 90.2 88.0 FiberStrength 3570 4108 4376 4264 4727 4321 (MPa) Fiber Failure 4.0 4.5 4.84.7 5.2 4.9 Strain (%) Specific Fiber 3.5 3.6 3.6 3.5 3.5 3.4 Modulus(×10⁶ m) Specific Fiber 1.4 1.6 1.7 1.7 1.8 1.7 Strength (×10⁵ m) 7 8 910 11 12 SiO₂ 61.37 61.46 61.37 59.74 59.73 59.73 Al₂O₃ 15.57 15.3615.57 16.00 17.46 17.46 Fe₂O₃ 0.29 0.29 0.29 0.27 0.29 0.29 CaO 12.5113.18 12.51 9.63 7.46 7.46 MgO 6.21 6.26 6.21 8.58 7.13 7.13 Na₂O 0.050.05 0.05 0.19 0.19 0.19 K₂O 0.09 0.09 0.09 0.09 0.09 0.09 Sc₂O₃ 0.000.00 0.00 4.24 6.34 4.44 Y₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 La₂O₃ 2.680.00 0.00 0.00 0.00 1.90 Nd₂O₃ 0.00 2.08 2.68 0.00 0.00 0.00 TiO₂ 0.510.50 0.51 0.63 0.69 0.69 Li₂O 0.72 0.72 0.72 0.61 0.61 0.61 SO₃ 0.010.01 0.01 0.02 0.02 0.02 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.000.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00 100.00 100.00 100.00T_(L) (° C.) 1198 1201 1201 1355 1376 T_(F) (° C.) 1309 1300 1308 13081349 1315 ΔT (° C.) 111 99 107 −47 −61 T_(m) (° C.) 1515 1506 1513 14911515 1507 Fiber Density 2.63 2.62 2.62 2.63 (g/cm³) Fiber Modulus 88.488.1 88.9 92.1 (GPa) Fiber Strength 4639 (MPa) Fiber Failure 5.3 Strain(%) Specific Fiber 3.4 3.4 3.5 3.6 Modulus (×10⁶ m) Specific Fiber 1.8Strength (×10⁵ m) 13 14 15 16 17 18 SiO₂ 59.73 59.74 59.73 59.73 59.7359.73 Al₂O₃ 17.46 16.00 17.46 17.46 17.46 17.46 Fe₂O₃ 0.29 0.27 0.290.29 0.29 0.29 CaO 7.46 9.63 7.46 7.46 7.46 7.46 MgO 7.13 8.58 7.13 7.137.13 7.13 Na₂O 0.19 0.19 0.19 0.19 0.19 0.19 K₂O 0.09 0.09 0.09 0.090.09 0.09 Sc₂O₃ 3.17 0.00 0.00 0.00 0.00 4.44 Y₂O₃ 0.00 4.24 6.34 4.443.17 0.00 La₂O₃ 3.17 0.00 0.00 1.90 3.17 0.00 Nd₂O₃ 0.00 0.00 0.00 0.000.00 0.00 TiO₂ 0.69 0.63 0.69 0.69 0.69 2.59 Li₂O 0.61 0.61 0.61 0.610.61 0.61 SO₃ 0.02 0.02 0.02 0.02 0.02 0.02 ZrO₂ 0.00 0.00 0.00 0.000.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00100.00 100.00 100.00 T_(L) (° C.) 1302 1194 1194 1193 1197 T_(F) (° C.)1317 1287 1327 1326 1330 ΔT (° C.) 15 93 133 133 133 T_(m) (° C.) 15121476 1515 1523 1532 Fiber Density 2.64 2.65 2.65 2.65 2.65 (g/cm³) FiberModulus 91.8 92.1 92.2 91.5 91.9 (GPa) Fiber Strength 5255 5181 5195(MPa) Fiber Failure 5.7 5.7 5.7 Strain (%) Specific Fiber 3.5 3.5 3.53.5 3.5 Modulus (×10⁶ m) Specific Fiber 2.0 2.0 2.0 Strength (×10⁵ m) 1920 21 22 23 24 SiO₂ 59.73 60.31 60.22 59.85 59.85 60.37 Al₂O₃ 17.4615.62 16.28 15.58 15.58 14.48 Fe₂O₃ 0.29 0.23 0.28 0.27 0.27 0.25 CaO7.46 13.84 13.06 11.05 11.05 5.46 MgO 7.13 8.63 8.61 8.70 8.70 8.03 Na₂O0.19 0.06 0.06 0.20 0.20 0.18 K₂O 0.09 0.07 0.09 0.09 0.09 0.08 Sc₂O₃4.44 0.00 0.00 2.88 0.00 0.00 Y₂O₃ 0.00 0.00 0.00 0.00 2.88 0.00 La₂O₃0.00 0.00 0.00 0.00 0.00 9.87 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂0.69 0.45 0.64 0.61 0.61 0.57 Li₂O 0.61 0.78 0.75 0.76 0.76 0.70 SO₃0.02 0.02 0.02 0.02 0.02 0.01 ZrO₂ 1.90 0.00 0.00 0.00 0.00 0.00 B₂O₃TOTAL 100.00 100.00 100.00 100.00 100.00 100.00 T_(L) (° C.) 1211 12251240 1195 1260 T_(F) (° C.) 1251 1265 1264 1268 1320 ΔT (° C.) 40 40 2473 60 T_(m) (° C.) 1441 1457 1450 1458 1523 Fiber Density 2.62 2.62 2.642.64 2.70 (g/cm³) Fiber Modulus 90.2 90.5 92.4 91.1 89.5 (GPa) FiberStrength 4622 4739 4913 4759 4978 (MPa) Fiber Failure 5.13 5.2 5.3 5.25.6 Strain (%) Specific Fiber 3.51 3.5 3.6 3.5 3.4 Modulus (×10⁶ m)Specific Fiber 1.8 1.9 1.9 1.8 1.9 Strength (×10⁵ m) 25 26 27 28 29 30SiO₂ 59.54 59.73 59.77 62.85 54.20 59.94 Al₂O₃ 17.28 17.35 17.36 19.7815.20 15.66 Fe₂O₃ 0.30 0.29 0.28 0.32 0.26 0.25 CaO 9.68 4.99 0.69 2.776.41 13.03 MgO 11.28 11.25 11.20 7.00 6.73 7.80 Na₂O 1.12 1.12 1.12 2.400.03 0.03 K₂O 0.10 0.09 0.09 0.00 0.07 0.09 Sc₂O₃ 0.00 0.00 0.00 3.163.88 0.00 Y₂O₃ 0.00 0.00 0.00 0.00 0.00 1.99 La₂O₃ 0.00 4.49 8.78 0.003.88 0.00 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.68 0.68 0.68 0.780.02 0.52 Li₂O 0.00 0.00 0.00 0.00 0.59 0.65 SO₃ 0.02 0.02 0.02 0.020.02 0.02 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.00 0.938.71 0 TOTAL 100.00 100.00 100.00 100.00 100.00 100.00 T_(L) (° C.) 12651268 1324 1344 1300 1211 T_(F) (° C.) 1285 1316 1361 1397 1414 1275 ΔT(° C.) 20 48 37 53 114 64 T_(m) (° C.) 1471 1508 1559 1613 1631 1466Fiber Density 2.61 2.64 2.67 2.51 2.53 2.64 (g/cm³) Fiber Modulus 90.090.5 90.1 87.1 85.9 90.4 (GPa) Fiber Strength 5105 5294 5445 5503 5492(MPa) Fiber Failure 5.7 5.9 6.0 6.3 6.4 Strain (%) Specific Fiber 3.53.5 3.4 3.5 3.5 3.5 Modulus (×10⁶ m) Specific Fiber 2.0 2.0 2.1 2.2 2.2Strength (×10⁵ m) 31 32 33 34 35 36 SiO₂ 59.94 59.94 60.85 61.67 61.6759.52 Al₂O₃ 15.66 15.66 15.90 16.33 16.33 17.24 Fe₂O₃ 0.25 0.25 0.250.26 0.26 0.27 CaO 13.03 13.03 13.23 6.01 6.01 6.35 MgO 7.80 7.80 7.9210.26 10.26 10.85 Na₂O 0.03 0.03 0.03 0.16 0.16 0.17 K₂O 0.09 0.09 0.100.09 0.09 0.10 Sc₂O₃ 0.00 1.99 0.51 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 0.004.21 0.00 4.44 La₂O₃ 1.99 0.00 0.00 0.00 4.21 0.00 Nd₂O₃ 0.00 0.00 0.000.00 0.00 0.00 TiO₂ 0.52 0.52 0.53 0.58 0.58 0.61 Li₂O 0.65 0.65 0.660.42 0.42 0.44 SO₃ 0.02 0.02 0.02 0.00 0.00 0.00 ZrO₂ 0.00 0.00 0.000.00 0.00 0.00 B₂O₃ 0 0 0 0 0 0 TOTAL 100.00 100.00 100.00 100.00 100.00100.00 T_(L) (° C.) 1209 1212 1213 1258 1247 1232 T_(F) (° C.) 1265 12631270 1329 1331 1300 ΔT (° C.) 56 51 57 71 84 68 T_(m) (° C.) 1458 14511466 1529 1535 1489 Fiber Density 2.64 2.64 2.62 2.62 2.65 (g/cm³) FiberModulus 90.6 90.3 92.2 90.9 94.1 (GPa) Fiber Strength 5224 (MPa) FiberFailure 5.6 Strain (%) Specific Fiber 3.5 3.5 3.6 3.5 3.6 Modulus (×10⁶m) Specific Fiber 2.0 Strength (×10⁵ m) 37 38 39 40 41 42 SiO₂ 59.5259.00 59.52 60.36 59.84 61.69 Al₂O₃ 17.24 17.25 17.40 17.65 18.14 21.64Fe₂O₃ 0.27 0.29 0.29 0.29 0.30 0.34 CaO 6.35 6.18 5.37 4.05 3.57 1.01MgO 10.85 10.65 10.73 10.86 11.85 10.12 Na₂O 0.17 0.02 0.02 0.02 0.020.02 K₂O 0.10 0.09 0.09 0.09 0.09 0.11 Sc₂O₃ 0.00 0.00 0.00 0.00 0.000.00 Y₂O₃ 0.00 5.84 5.90 5.98 5.47 4.21 La₂O₃ 4.44 0.00 0.00 0.00 0.000.00 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.61 0.68 0.68 0.69 0.710.85 Li₂O 0.44 0.00 0.00 0.00 0.00 0.00 SO₃ 0.00 0.00 0.00 0.00 0.000.00 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 0.000.00 TOTAL 100.00 100.00 100.00 100.00 100.00 100.00 T_(L) (° C.) 12371276 1297 1336 1316 T_(F) (° C.) 1302 1315 1324 1340 1332 1392 ΔT (° C.)65 39 27 4 16 T_(m) (° C.) 1496 1500 1509 1529 1518 1599 T_(soft)(° C.)951 958 978 962 995 CTE (10⁻⁶/° C.) 3.1 Fiber Density 2.66 2.63 2.662.65 2.65 2.58 (g/cm³) Fiber Modulus 92.8 92.8 93.2 94.1 93.6 92.4 (GPa)Fiber Strength 5076 (MPa) Fiber Failure 5.5 Strain (%) Specific Fiber3.6 3.6 3.6 3.6 3.6 3.6 Modulus (×10⁶ m) Specific Fiber 2.0 Strength(×10⁵ m) 43 44 45 46 47 48 SiO₂ 61.69 60.82 60.82 59.40 60.03 60.48Al₂O₃ 21.64 21.34 21.34 17.25 17.40 17.67 Fe₂O₃ 0.34 0.34 0.34 0.25 0.260.26 CaO 1.01 0.99 0.99 5.78 5.93 4.95 MgO 10.12 9.98 9.98 10.78 10.8310.64 Na₂O 0.02 0.02 0.02 0.05 0.04 0.04 K₂O 0.11 0.11 0.11 0.10 0.100.10 Sc₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 5.56 0.00 4.79 4.034.34 La₂O₃ 4.21 0.00 5.56 0.00 0.00 0.00 Nd₂O₃ 0.00 0.00 0.00 0.00 0.000.00 TiO₂ 0.85 0.84 0.84 0.52 0.57 0.56 Li₂O 0.00 0.00 0.00 1.06 0.810.95 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 ZrO₂ 0.00 0.00 0.00 0.00 0.000.00 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.00 100.00100.00 100.00 100.00 T_(L) (° C.) 1235 1237 1232 T_(F) (° C.) 1401 13971390 1273 1289 1299 ΔT (° C.) 38 52 67 T_(soft)(° C.) 992 993 990 T_(m)(° C.) 1603 1595 1589 1467 1484 1499 Fiber Density 2.58 2.60 2.61 2.652.64 2.63 (g/cm³) Fiber Modulus 91.6 92.7 92.0 94.7 93.8 93.1 (GPa)Fiber Strength 5307 5237 5357 (MPa) Fiber Failure 5.6 5.6 5.8 Strain (%)Specific Fiber 3.6 3.6 3.6 3.6 3.6 3.6 Modulus (×10⁶ m) Specific Fiber2.0 2.0 2.1 Strength (×10⁵ m) Dielectric 5.69 5.82 5.87 Constant @ 1 GHzDissipation loss @ 0.0020 0.0018 0.0017 1 GHz 49 50 51 52 53 54 SiO₂59.90 56.85 54.76 57.72 60.07 59.40 Al₂O₃ 16.54 15.70 15.12 16.67 17.5617.25 Fe₂O₃ 0.24 0.23 0.22 0.22 0.22 0.25 CaO 5.38 5.10 4.92 4.63 4.655.78 MgO 11.55 10.96 10.56 9.94 9.97 10.78 Na₂O 0.05 0.04 0.04 0.06 0.070.05 K₂O 0.10 0.09 0.09 0.11 0.12 0.10 Sc₂O₃ 0.00 0.00 0.00 0.00 0.000.00 Y₂O₃ 4.71 9.56 12.89 8.67 4.88 2.40 La₂O₃ 0.00 0.00 0.00 0.00 0.002.40 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.50 0.48 0.46 0.43 0.390.52 Li₂O 1.03 0.98 0.94 1.55 2.08 1.06 SO₃ 0.00 0.00 0.00 0.00 0.000.01 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 0.000.00 TOTAL 100.00 100.00 100.00 100.00 100.00 100.01 T_(L) (° C.) 12521223 1225 1201 1216 1240 T_(F) (° C.) 1273 1247 1232 1252 1262 1273 ΔT(° C.) 21 24 7 51 46 33 T_(m) (° C.) 1464 1427 1403 1441 1465 1467 FiberDensity 2.65 2.74 2.81 2.71 (g/cm³) Fiber Modulus 93.8 96.4 97.6 95.3(GPa) Fiber Strength 5013 (MPa) Fiber Failure 5.3 Strain (%) SpecificFiber 3.6 3.6 3.5 3.6 Modulus (×10⁶ m) Specific Fiber 1.8 Strength (×10⁵m) 55 56 57 58 59 60 SiO₂ 59.40 60.03 60.03 60.16 60.16 59.43 Al₂O₃17.25 17.40 17.40 18.32 18.32 18.10 Fe₂O₃ 0.25 0.26 0.26 0.28 0.28 0.27CaO 5.78 5.93 5.93 5.43 5.43 5.36 MgO 10.78 10.83 10.83 10.19 10.1910.07 Na₂O 0.05 0.04 0.04 0.04 0.04 0.04 K₂O 0.10 0.10 0.10 0.11 0.110.10 Sc₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 2.02 0.00 4.09 0.000.00 La₂O₃ 4.79 2.02 4.03 0.00 4.09 5.25 Nd₂O₃ 0.00 0.00 0.00 0.00 0.000.00 TiO₂ 0.52 0.57 0.57 0.61 0.61 0.60 Li₂O 1.06 0.81 0.81 0.79 0.790.78 SO₃ 0.01 0.01 0.01 0.00 0.00 0.00 ZrO₂ 0.00 0.00 0.00 0.00 0.000.00 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.00 100.01 100.00100.00 100.00 100.00 T_(L) (° C.) 1245 1240 1245 1233 1233 1227 T_(F) (°C.) 1275 1288 1290 1305 1302 1298 ΔT (° C.) 30 48 45 71 69 71 T_(m) (°C.) 1473 1483 1487 1503 1503 1495 Fiber Density 2.64 2.64 2.63 2.63 2.65(g/cm³) Fiber Modulus 93.1 92.9 92.8 91.4 91.6 (GPa) Fiber Strength 5368(MPa) Fiber Failure 5.8 Strain (%) Specific Fiber 3.60 3.6 Modulus (×10⁶m) Specific Fiber 2.1 Strength (×10⁵ m) 61 62 63 64 65 66 SiO₂ 59.9960.51 60.39 60.20 59.60 58.69 Al₂O₃ 17.86 15.46 15.43 15.39 15.23 15.00Fe₂O₃ 0.27 0.26 0.26 0.26 0.25 0.25 CaO 4.49 14.49 14.46 14.42 14.2714.05 MgO 9.92 8.17 8.15 8.13 8.05 7.93 Na₂O 0.04 0.03 0.03 0.03 0.030.03 K₂O 0.10 0.09 0.09 0.09 0.09 0.09 Sc₂O₃ 0.00 0.00 0.00 0.00 0.000.00 Y₂O₃ 0.00 0.00 0.20 0.50 1.50 3.00 La₂O₃ 5.97 0.00 0.00 0.00 0.000.00 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.59 0.55 0.54 0.54 0.540.53 Li₂O 0.77 0.43 0.43 0.43 0.43 0.42 SO₃ 0.00 0.01 0.01 0.01 0.010.01 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 0.000.00 TOTAL 100.00 99.99 99.99 99.99 99.99 99.99 T_(L) (° C.) 1240 12051208 1200 1202 1209 T_(F) (° C.) 1316 1273 1268 1271 1269 1256 ΔT (° C.)76 68 60 71 67 47 T_(m) (° C.) 1518 1468 1462 1465 1459 1440 FiberDensity 2.65 2.63 (g/cm³) Fiber Modulus 91.8 89.5 (GPa) Fiber Strength(MPa) Fiber Failure Strain (%) Specific Fiber 3.5 Modulus (×10⁶ m)Specific Fiber Strength (×10⁵ m) 67 68 69 70 71 72 SiO₂ 58.08 57.4856.27 60.39 60.20 59.60 Al₂O₃ 14.84 14.69 14.38 15.43 15.39 15.23 Fe₂O₃0.25 0.24 0.24 0.26 0.26 0.25 CaO 13.91 13.76 13.47 14.46 14.42 14.27MgO 7.84 7.76 7.60 8.15 8.13 8.05 Na₂O 0.03 0.03 0.03 0.03 0.03 0.03 K₂O0.09 0.09 0.09 0.09 0.09 0.09 Sc₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃4.00 5.00 7.00 0.00 0.00 0.00 La₂O₃ 0.00 0.00 0.00 0.20 0.50 1.50 Nd₂O₃0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.52 0.52 0.51 0.54 0.54 0.54 Li₂O0.42 0.41 0.40 0.43 0.43 0.43 SO₃ 0.01 0.01 0.01 0.01 0.01 0.01 ZrO₂0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL99.99 100.00 100.00 99.99 99.99 99.99 T_(L) (° C.) 1206 1208 1212 12071205 1204 T_(F) (° C.) 1260 1255 1244 1265 1265 1259 ΔT (° C.) 54 47 3258 60 55 T_(m) (° C.) 1444 1463 1480 1456 1457 1447 Fiber Density(g/cm³) Fiber Modulus (GPa) Fiber Strength (MPa) Fiber Failure Strain(%) Specific Fiber Modulus (×10⁶ m) Specific Fiber Strength (×10⁵ m) 7374 75 76 77 78 79 80 SiO₂ 58.69 58.08 57.48 56.27 60.72 60.81 58.9158.91 Al₂O₃ 15.00 14.84 14.69 14.38 15.57 13.01 16.95 16.95 Fe₂O₃ 0.250.25 0.24 0.24 0.27 0.23 0.25 0.25 CaO 14.05 13.91 13.76 13.47 22.5219.17 4.35 4.35 MgO 7.93 7.84 7.76 7.60 0.19 0.16 10.49 10.49 Na₂O 0.030.03 0.03 0.03 0.01 0.01 0.04 0.04 K₂O 0.09 0.09 0.09 0.09 0.08 0.070.10 0.10 Sc₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.000.00 0.00 0.00 6.01 3.98 0.00 La₂O₃ 3.00 4.00 5.00 7.00 0.00 0.00 0.003.98 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 TiO₂ 0.53 0.52 0.520.51 0.63 0.53 2.09 2.09 Li₂O 0.42 0.42 0.41 0.40 0.00 0.00 0.78 0.78SO₃ 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 ZrO₂ 0.00 0.00 0.00 0.000.00 0.00 2.05 2.05 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL99.99 99.99 100.00 100.00 100.00 100.00 100.00 100.00 T_(L) (° C.) 12021199 1196 1231 1272 T_(F) (° C.) 1253 1248 1245 1325 1346 1297 1298 ΔT(° C.) 51 49 49 94 74 T_(m) (° C.) 1440 1432 1427 1528 1543 1491 1496T_(soft)(° C.) 943 962 912 904 T_(g) (° C.6) 722 716 CTE (10⁻⁶/° C.)4.11 4.13 Fiber Density 2.62 2.68 2.66 2.66 (g/cm³) Fiber Modulus 82.083.7 93.8 92.4 (GPa) Fiber Strength 3948 4029 (MPa) Fiber Failure 4.84.8 Strain (%) Specific Fiber 3.2 3.2 3.6 3.5 Modulus (×10⁶ m) SpecificFiber 1.5 1.5 Strength (×10⁵ m) 81 82 83 84 85 86 87 88 89 SiO₂ 61.4359.81 59.04 58.66 57.41 58.17 54.56 56.41 51.18 Al₂O₃ 15.14 14.74 14.5514.45 14.15 14.33 13.44 13.90 12.61 Fe₂O₃ 0.26 0.26 0.25 0.25 0.25 0.250.23 0.24 0.22 CaO 14.70 12.52 11.46 10.95 10.72 12.17 9.36 11.80 8.78MgO 7.98 7.77 7.67 7.62 7.45 7.55 7.08 7.32 6.65 Na₂O 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 K₂O 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 Sc₂O₃ 0.00 4.43 6.56 7.60 9.56 0.00 0.00 0.00 0.00 Y₂O₃ 0.000.00 0.00 0.00 0.00 7.05 14.88 0.00 0.00 La₂O₃ 0.00 0.00 0.00 0.00 0.000.00 0.00 9.87 20.15 Nd₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00TiO₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li₂O 0.49 0.48 0.470.47 0.46 0.47 0.44 0.45 0.41 SO₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 ZrO₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.0 100.0 100.0 100.0100.0 100.0 100.0 100.0 100.0 T_(L) (° C.) 1199 1337 1434 1462 1516 12041294 1184 1158 T_(F) (° C.) 1296 1285 1284 1307 1348 1280 1260 1266 1237ΔT (° C.) 97 −52 −150 −155 −168 76 −34 82 79 T_(m) (° C.) 1495 1471 14581447 1449 1464 1426 1450 1406 T_(soft) (° C.) 898 917 920 925 931 911922 899 903 T_(g) (° C.) 717 740 750 759 757 734 748 721 729 CTE (10⁻⁶/°C.) 4.63 4.61 4.54 4.54 4.44 Fiber Density 2.60 2.64 2.70 2.78 (g/cm³)Fiber Modulus 89.4 92.4 91.6 90.8 (GPa) Fiber Strength (MPa) FiberFailure Strain (%) Specific Fiber 3.5 3.6 3.5 3.3 Modulus (×10⁶ m)Specific Fiber Strength (×10⁵ m) 90 91 92 93 SiO₂ 63.08 65.03 65.0364.49 Al₂O₃ 16.16 15.35 15.35 14.61 Fe₂O₃ 0.24 0.23 0.23 0.19 CaO 4.403.37 3.37 3.00 MgO 10.63 10.86 10.86 9.67 Na₂O 0.04 0.04 0.04 0.03 K₂O0.09 0.09 0.09 0.08 Sc₂O₃ 0.00 0.00 0.00 0.00 Y₂O₃ 0.00 0.00 3.68 0.00La₂O₃ 4.04 3.68 0.00 4.33 Nd₂O₃ 0.00 0.00 0.00 0.00 TiO₂ 0.52 0.47 0.470.39 Li₂O 0.79 0.89 0.89 0.79 SO₃ 0.00 0.00 0.00 0.00 ZrO₂ 0.00 0.000.00 0.00 B₂O₃ 0.00 0.00 0.00 0.00 P₂O₅ 0.00 0.00 0.00 2.42 TOTAL 100.0100.0 100.0 100.0 T_(L) (° C.) 1267 T_(F) (° C.) 1332 1355 1350 1396 ΔT(° C.) 65 T_(m) (° C.) 1542 1572 1562 1619 Fiber Density 2.60 2.55(g/cm³) Fiber Modulus 91.4 87.7 (GPa) Fiber Strength (MPa) Fiber FailureStrain (%) Specific Fiber 3.6 3.5 Modulus (×10⁶ m) Specific FiberStrength (×10⁵ m)

Certain of these data were plotted in FIGS. 1-4. FIG. 1 is a chartshowing Young's modulus values relative to the amount of rare earthoxides (RE₂O₃) for the glass compositions in Examples 1-17, 22, and 23.FIG. 2 is a chart showing pristine fiber tensile strength valuesrelative to the amount of rare earth oxides (RE₂O₃) for the glasscompositions in Examples 1-17, 22, and 23. FIG. 3 is a chart showingsoftening and glass transition temperatures relative to the amount ofrare earth oxides (RE₂O₃) for the glass compositions of Examples 81-89.FIG. 4 is a chart showing linear coefficient of thermal expansionrelative to the amount of scandium oxide (Sc₂O₃) for the glasscompositions of Examples 81-89.

TABLE 2 94 95 96 97 98 99 SiO₂ 61.43 62.43 63.79 64.73 65.50 66.19 Al₂O₃17.40 16.96 17.33 17.59 15.91 14.41 Fe₂O₃ 0.28 0.27 0.27 0.27 0.25 0.23CaO 3.71 3.61 1.54 0.11 0.12 0.13 MgO 11.96 11.66 11.88 12.04 12.7613.41 Na₂O 0.03 0.03 0.03 0.03 0.03 0.03 K₂O 0.10 0.09 0.09 0.09 0.080.08 Sc₂O₃ 0 0 0 0 0 0 Y₂O₃ 0 0 0 0 0 0 La₂O₃ 4.05 3.95 4.03 4.09 4.344.56 Nd₂O₃ 0 0 0 0 0 0 TiO₂ 0.62 0.61 0.62 0.63 0.56 0.50 Li₂O 0.41 0.400.41 0.42 0.44 0.47 SO₃ 0 0 0 0 0 0 ZrO₂ 0 0 0 0 0 0 B₂O₃ 0 0 0 0 0 0TOTAL 100 100 100 100 100 100 T_(L) (° C.) 1276 1305 1348 1378 1405 1424T_(F) (° C.) 1323 1337 1388 1367 1384 1379 ΔT (° C.) 47 32 40 −11 −21−45 T_(m) (° C.) 1517 1536 1597 1571 1592 1589 Fiber Density (g/cm³)Fiber Modulus (GPa) Fiber Strength (MPa) Fiber Failure Strain (%)Specific Fiber Modulus (×10⁶ m) Specific Fiber Strength (×10⁵ m) 100 101102 103 104 105 SiO₂ 66.94 66.51 65.59 65.21 61.43 62.43 Al₂O₃ 17.2817.08 16.85 18.89 17.40 16.96 Fe₂O₃ 0.21 0.20 0.19 0.13 0.28 0.27 CaO0.11 0.11 0.11 0.10 3.71 3.61 MgO 10.46 10.67 10.52 7.75 11.96 11.66Na₂O 0.07 0.08 0.08 0.14 0.03 0.03 K₂O 0.11 0.11 0.11 0.15 0.10 0.09Sc₂O₃ 0 0 0 0 0 0 Y₂O₃ 0 0 0 0 4.05 3.95 La₂O₃ 2.42 2.67 4.00 2.95 0 0Nd₂O₃ 0 0 0 0 0 0 TiO₂ 0.39 0.35 0.34 0.08 0.62 0.61 Li₂O 2.02 2.23 2.204.59 0.41 0.40 SO₃ 0 0 0 0 0 0 ZrO₂ 0 0 0 0 0 0 B₂O₃ 0 0 0 0 0 0 TOTAL100 100 100 100 100 100 T_(L) (° C.) 1254 1265 1285 1310 T_(F) (° C.)1377 1362 1321 1334 ΔT (° C.) 123 97 36 24 T_(m) (° C.) 1605 1590 15151532 Fiber Density 2.49 2.49 (g/cm³) Fiber Modulus (GPa) Fiber 5262 5335Strength (MPa) Fiber Failure Strain (%) Specific Fiber Modulus (×10⁶ m)Specific Fiber 2.2 2.2 Strength (×10⁵ m) 106 107 108 109 110 111 SiO₂63.79 64.73 65.50 66.19 66.94 66.51 Al₂O₃ 17.33 17.59 15.91 14.41 17.2817.08 Fe₂O₃ 0.27 0.27 0.25 0.23 0.21 0.20 CaO 1.54 0.11 0.12 0.13 0.110.11 MgO 11.88 12.04 12.76 13.41 10.46 10.67 Na₂O 0.03 0.03 0.03 0.030.07 0.08 K₂O 0.09 0.09 0.08 0.08 0.11 0.11 Sc₂O₃ 0 0 0 0 0 0 Y₂O₃ 4.034.09 4.34 4.56 2.42 2.67 La₂O₃ 0 0 0 0 0 0 Nd₂O₃ 0 0 0 0 0 0 TiO₂ 0.620.63 0.56 0.50 0.39 0.35 Li₂O 0.41 0.42 0.44 0.47 2.02 2.23 SO₃ 0 0 0 00 0 ZrO₂ 0 0 0 0 0 0 B₂O₃ 0 0 0 0 0 0 TOTAL 100 100 100 100 100 100T_(L) (° C.) 1361 1391 1412 1440 1270 1261 T_(F) (° C.) 1366 1385 13811375 1374 1358 ΔT (° C.) 5 −6 −31 −65 104 97 T_(m) (° C.) 1568 1590 15851581 1599 1582 Fiber Density 2.49 (g/cm³) Fiber Modulus (GPa) Fiber 5291Strength (MPa) Fiber Failure Strain (%) Specific Fiber Modulus (×10⁶ m)Specific Fiber 2.2 Strength (×10⁵ m) 112 113 114 115 116 117 SiO₂ 65.5965.21 60.52 60.52 60.52 60.52 Al₂O₃ 16.85 18.89 17.76 17.76 17.76 17.76Fe₂O₃ 0.19 0.13 0.28 0.28 0.28 0.28 CaO 0.11 0.10 4.99 4.99 4.99 4.99MgO 10.52 7.75 10.74 10.74 10.74 10.74 Na₂O 0.08 0.14 0.03 0.03 0.030.03 K₂O 0.11 0.15 0.10 0.10 0.10 0.10 Sc₂O₃ 0 0 0 0 0 0 Y₂O₃ 4.00 2.954.22 4.22 0 0 La₂O₃ 0 0 0 0 4.22 4.22 Nd₂O₃ 0 0 0 0 0 0 TiO₂ 0.34 0.080.63 0.63 0.63 0.63 Li₂O 2.20 4.59 0.50 0.50 0.50 0.50 SO₃ 0 0 0 0 0 0ZrO₂ 0 0 0 0 0 0 B₂O₃ 0 0 0 0 0 0 ZnO 0 0 3.22 0 3.22 0 SnO₂ 0 0 0 3.220 3.22 CeO₂ 0 0 0 0 0 4.09 TOTAL 100 100 100 100 100 100 T_(L) (° C.)1254 1293 T_(F) (° C.) 1347 1313 ΔT (° C.) 93 20 T_(m) (° C.) 1568 1547Fiber Density 2.49 (g/cm³) Fiber Modulus (GPa) Fiber 5284 Strength (MPa)Fiber Failure Strain (%) Specific Fiber Modulus (×10⁶ m) Specific Fiber2.2 Strength (×10⁵ m) 118 119 120 121 122 123 SiO₂ 60.52 60.34 57.3160.48 60.48 60.48 Al₂O₃ 17.76 11.16 10.60 17.67 17.67 17.67 Fe₂O₃ 0.280.22 0.21 0.26 0.26 0.26 CaO 4.99 11.86 11.26 4.95 4.95 4.95 MgO 10.7415.88 15.08 10.64 10.64 10.64 Na₂O 0.03 0.01 0.01 0.04 0.04 0.04 K₂O0.10 0.07 0.06 0.10 0.10 0.10 Sc₂O₃ 0 0 0 0 0 0 Y₂O₃ 0 0 0 0 0 0 La₂O₃ 00 5.05 0 0 0 Nd₂O₃ 4.22 0 0 0 0 0 Sm₂O₃ 0 0 0 0 4.34 0 Gd₂O₃ 0 0 0 0 04.34 TiO₂ 0.63 0.44 0.42 0.56 0.56 0.56 Li₂O 0.50 0 0 0.95 0.95 0.95 SO₃0 0.01 0 0 0 0 ZrO₂ 0 0 0 0 0 0 B₂O₃ 0 0 0 0 0 0 ZnO 0 0 0 0 0 0 SnO₂3.32 0 0 0 0 0 CeO₂ 0 0 0 4.34 0 0 Nb₂O₅ 0 0 0 0 0 0 TOTAL 100 100 100100 100 100 T_(L) (° C.) T_(F) (° C.) ΔT (° C.) T_(m) (° C.) FiberDensity (g/cm³) Fiber Modulus (GPa) Fiber Strength (MPa) Fiber FailureStrain (%) Specific Fiber Modulus (×10⁶ m) Specific Fiber Strength (×10⁵m) 124 SiO₂ 60.48 Al₂O₃ 17.67 Fe₂O₃ 0.26 CaO 4.95 MgO 10.64 Na₂O 0.04K₂O 0.10 Sc₂O₃ 0 Y₂O₃ 0 La₂O₃ 0 Nd₂O₃ 0 Sm₂O₃ 0 Gd₂O₃ 0 TiO₂ 0.56 Li₂O0.95 SO₃ 0 ZrO₂ 0 B₂O₃ 0 ZnO 0 SnO₂ 0 CeO₂ 0 Nb₂O₅ 4.34 TOTAL 100 T_(L)(° C.) T_(F) (° C.) ΔT (° C.) T_(m) (° C.) Fiber Density (g/cm³) FiberModulus (GPa) Fiber Strength (MPa) Fiber Failure Strain (%) SpecificFiber Modulus (×10⁶ m) Specific Fiber Strength (×10⁵ m)

TABLE 3 125 126 127 128 129 130 SiO₂ 61.42 60.85 60.07 61.02 61.28 60.18Al₂O₃ 17.85 17.62 17.52 17.80 17.87 16.77 Fe₂O₃ 0.37 0.37 0.37 0.38 0.380.37 CaO 5.42 5.64 5.92 6.00 6.01 7.18 MgO 8.81 9.18 9.63 8.22 6.29 8.05Na₂O 0.04 0.05 0.04 0.04 0.04 0.04 K₂O 0.11 0.10 0.10 0.11 0.11 0.10Y₂O₃ 4.45 4.64 4.87 4.94 4.96 4.93 TiO₂ 0.56 0.55 0.56 0.57 2.13 1.36Li₂O 0.96 1.00 0.91 0.93 0.93 1.01 Cu₂O 0.00 0.00 0.00 0.00 0.00 0.00SrO 0.00 0.00 0.00 0.00 0.00 0.00 TOTAL 100.0 100.0 100.0 100.0 100.0100.0 T_(L) (° C.) 1188 1188 1200 1185 1208 1154 T_(F) (° C.) 1319 13071297 1320 1338 1294 ΔT (° C.) 131 119 97 135 130 140 T_(m) (° C.) 15221508 1494 1521 1549 1493 Fiber Density 2.61 2.62 2.63 2.62 2.61 (g/cm³)Fiber Modulus 92.3 92.0 92.8 91.9 90.0 (GPa) Fiber Strength 5490 54925340 5467 (MPa) Fiber Failure 5.9 6.0 5.8 5.9 Strain (%) Specific Fiber3.6 3.6 3.6 3.6 3.5 Modulus (×10⁶ m) Specific Fiber 2.2 2.1 2.1 2.1 0.0Strength (×10⁵ m) 131 132 133 134 135 136 SiO₂ 61.28 60.18 60.83 60.1259.78 61.00 Al₂O₃ 17.87 16.77 15.23 17.84 17.99 16.75 Fe₂O₃ 0.38 0.370.37 0.39 0.40 0.25 CaO 6.01 7.18 7.90 5.88 5.93 4.67 MgO 6.29 8.05 8.869.47 9.55 10.20 Na₂O 0.04 0.04 0.04 0.04 0.04 0.04 K₂O 0.11 0.10 0.090.10 0.10 0.10 Y₂O₃ 4.96 4.93 4.50 4.80 4.84 3.25 TiO₂ 0.56 0.56 1.410.59 0.59 0.55 Li₂O 0.93 1.01 0.77 0.77 0.78 0.72 Cu₂O 1.57 0.80 0.000.00 0.00 0.00 SrO 0.00 0.00 0.00 0.00 0.00 2.46 TOTAL 100.0 100.0 100.0100.0 100.0 100.0 T_(L) (° C.) 1153 1167 1219 1226 1201 1235 T_(F) (°C.) 1336 1291 1289 1307 1299 1320 ΔT (° C.) 183 124 70 81 98 85 T_(m) (°C.) 1547 1447 1491 1501 1493 1519 Fiber Density 2.62 2.64 2.63 (g/cm³)Fiber Modulus 91.1 91.8 92.6 (GPa) Fiber Strength 5321 5243 5583 (MPa)Fiber Failure 5.8 5.7 6.03 Strain (%) Specific Fiber 3.5 3.5 3.6 Modulus(×10⁶ m) Specific Fiber 2.1 2.0 2.2 Strength (×10⁵ m)

Desirable characteristics that can be exhibited by various but notnecessarily all embodiments of the present invention can include, butare not limited to, the following: the provision of glass fibers, fiberglass strands, glass fiber fabrics, composites, and related productshaving a relatively low density; the provision of glass fibers, fiberglass strands, glass fiber fabrics, composites, and laminates having arelatively high tensile strength; the provision of glass fibers, fiberglass strands, glass fiber fabrics, composites, and related productshaving a relatively low density; the provision of glass fibers, fiberglass strands, glass fiber fabrics, composites, and laminates having arelatively high modulus; the provision of glass fibers, fiber glassstrands, glass fiber fabrics, composites, and laminates having arelatively high elongation; the provision of glass fibers, fiber glassstrands, glass fiber fabrics, prepregs, and other products useful forreinforcement applications; and others.

It is to be understood that the present description illustrates aspectsof the invention relevant to a clear understanding of the invention.Certain aspects of the invention that would be apparent to those ofordinary skill in the art and that, therefore, would not facilitate abetter understanding of the invention have not been presented in orderto simplify the present description. Although the present invention hasbeen described in connection with certain embodiments, the presentinvention is not limited to the particular embodiments disclosed, but isintended to cover modifications that are within the spirit and scope ofthe invention.

We claim:
 1. A glass composition suitable for fiber forming comprising:SiO₂ 56-68 weight percent; Al₂O₃ 11 to less than 20 weight percent; CaO12 weight percent or less; MgO 7-17 weight percent; Na₂O 0-1 weightpercent; K₂O 0-1 weight percent; Li₂O 0-5 weight percent; TiO₂ 0-2weight percent; B₂O₃ 0-3 weight percent; Fe₂O₃ 0-1 weight percent; SnO₂0-4 weight percent; ZnO 0-4 weight percent;

at least one rare earth oxide in an amount not less than 1 weightpercent; wherein the at least one rare earth oxide is selected from thegroup consisting of La₂O₃, Y₂O₃, Sc₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃, andother constituents 0-11 weight percent total.
 2. The glass compositionof claim 1, wherein Al₂O₃ is 14-less than 20 weight percent.
 3. Theglass composition of claim 1, wherein MgO is 10-17 weight percent. 4.The glass composition of claim 1, wherein CaO is less than about 5weight percent.
 5. The glass composition of claim 1, whereinNa₂O+K₂O+Li₂O is greater than 1 weight percent.
 6. The glass compositionof claim 5, wherein Na₂O+K₂O is less than about 0.5 weight percent. 7.The glass composition of claim 1, wherein Na₂O+K₂O is less than about0.5 weight percent.
 8. The glass composition of claim 1, wherein Li₂O isabout 0.4-about 2 weight percent.
 9. The glass composition of claim 1,wherein SiO₂ is at least 60 weight percent.
 10. The glass composition ofclaim 1, wherein the at least one rare earth oxide is at least 3 weightpercent.
 11. The glass composition of claim 1, wherein the at least onerare earth oxide is up to about 8 weight percent.
 12. The glasscomposition of claim 1, wherein the at least one rare earth oxide is upto about 5 weight percent.
 13. The glass composition of claim 1, whereinZnO is >0-4 weight percent.
 14. The glass composition of claim 1,wherein SnO₂ is >0-4 weight percent.
 15. The glass composition of claim1, wherein CeO₂ is >0-4 weight percent.
 16. The glass composition ofclaim 1, wherein SnO₂+CeO₂ is >0-8 weight percent.
 17. The glasscomposition of claim 1, wherein the composition is substantially free ofB₂O₃.
 18. The glass composition of claim 1, further comprising Nb₂O₅ inan amount of >0-5 weight percent.
 19. A glass composition suitable forfiber forming comprising: SiO₂ 60-68 weight percent; Al₂O₃ 14-19 weightpercent; CaO 5 weight percent or less; MgO 10-16 weight percent; Na₂O0-1 weight percent; K₂O 0-1 weight percent; Li₂O 0-2 weight percent;TiO₂ 0-2 weight percent; B₂O₃ 0-3 weight percent; Fe₂O₃ 0-1 weightpercent; SnO₂ 0-4 weight percent; ZnO 0-4 weight percent;

at least one rare earth oxide in an amount not less than 1 weightpercent; and other constituents 0-11 weight percent total.
 20. The glasscomposition of claim 19, wherein the at least one rare earth oxide is atleast 3 weight percent.
 21. The glass composition of claim 19, whereinthe at least one rare earth oxide is up to about 8 weight percent. 22.The glass composition of claim 19, wherein the at least one rare earthoxide is up to about 5 weight percent.
 23. The glass composition ofclaim 19, wherein the at least one rare earth oxide comprises at leastone of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃.
 24. The glasscomposition of claim 19, wherein ZnO is >0-4 weight percent.
 25. Theglass composition of claim 19, wherein SnO₂ is >0-4 weight percent. 26.The glass composition of claim 23, wherein CeO₂ is >0-4 weight percent.27. The glass composition of claim 23, wherein SnO₂+CeO₂ is >0 and 8weight percent.
 28. The glass composition of claim 19, wherein thecomposition is substantially free of B₂O₃.
 29. The glass composition ofclaim 19, further comprising Nb₂O₅ in an amount of >0-about 5 weightpercent.
 30. A glass composition suitable for fiber forming comprising:SiO₂ 60-68 weight percent; Al₂O₃ 14-19 weight percent; CaO 5 weightpercent or less; MgO 10-16 weight percent; Na₂O 0-1 weight percent; K₂O0-1 weight percent; Li₂O 0.4-2 weight percent; TiO₂ 0-2 weight percent;B₂O₃ 0-3 weight percent; Fe₂O₃ 0-1 weight percent; SnO₂ 0-4 weightpercent; ZnO 0-4 weight percent;

at least one rare earth oxide in an amount between not less than 1 toabout 8 weight percent; and other constituents 0-11 weight percenttotal, wherein Na₂O+K₂O is not less than 0.05 weight percent.
 31. Theglass composition of claim 30, wherein the at least one rare earth oxideis at least 3 weight percent.
 32. The glass composition of claim 30,wherein the at least one rare earth oxide is up to about 5 weightpercent.
 33. The glass composition of claim 30, wherein the at least onerare earth oxide comprises at least one of La₂O₃, Y₂O₃, Sc₂O₃, Nd₂O₃,CeO₂, Sm₂O₃, and Gd₂O₃.
 34. The glass composition of claim 33, whereinCeO₂ is >0-4 weight percent.
 35. The glass composition of claim 33,wherein SnO₂+CeO₂ is >0-8 weight percent.
 36. The glass composition ofclaim 30, wherein ZnO is >0-4 weight percent.
 37. The glass compositionof claim 30, wherein SnO₂>0-4 weight percent.
 38. The glass compositionof claim 30, wherein the composition is substantially free of B₂O₃. 39.The glass composition of claim 30, further comprising Nb₂O₅ in an amountof >0-5 weight percent.
 40. A glass composition suitable for fiberforming comprising: SiO₂ 59-62 weight percent; Al₂O₃ 14-19 weightpercent; CaO 4-8 weight percent; MgO 6-11 weight percent; Na₂O 0-1weight percent; K₂O 0-1 weight percent; Li₂O 0-2 weight percent; TiO₂0-3 weight percent; B₂O₃ 0-3 weight percent; Fe₂O₃ 0-1 weight percent;Cu₂O 0-2 weight percent; SrO 0-3 weight percent;

at least one rare earth oxide in an amount not less than 3 weightpercent; wherein the at least one rare earth oxide is selected from thegroup consisting of La₂O₃, Y₂O₃, Sc₂O₃, CeO₂, Sm₂O₃, and Gd₂O₃, andother constituents 0-11 weight percent total.
 41. The glass compositionof claim 40, wherein the at least one rare earth oxide is at least 4weight percent.
 42. The glass composition of claim 40, wherein the atleast one rare earth oxide is up to about 8 weight percent.
 43. Theglass composition of claim 40, wherein the at least one rare earth oxideis up to about 5 weight percent.
 44. The glass composition of claim 40,wherein SrO is >0-3 weight percent.
 45. The glass composition of claim40, wherein Cu₂O is >0-2 weight percent.
 46. The glass composition ofclaim 40, wherein Y₂O₃ is >0-5 weight percent.
 47. The glass compositionof claim 40, wherein Cu₂O+SrO is >0-5 weight percent.
 48. The glasscomposition of claim 40, wherein the composition is substantially freeof B₂O₃.